Trigonometry

112 soru

Soru 21Soru →

What is the period of the function f(x)=4cos⁡(13x)f(x) = 4\cos\left(\frac{1}{3}x\right)?

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Cevap: 6π6\pi

Cevap

The period of the function is 6π6\pi.
The standard period of the cosine function y=cos⁡(x)y = \cos(x) is 2π2\pi. For a transformed trigonometric function of the form y=Acos⁡(Bx)y = A\cos(Bx), the period is given by the formula 2π∣B∣\frac{2\pi}{|B|}. In the function f(x)=4cos⁡(13x)f(x) = 4\cos\left(\frac{1}{3}x\right), the coefficient of xx is B=13B = \frac{1}{3}. Dividing the standard period 2π2\pi by 13\frac{1}{3} yields a period of 2π×3=6π2\pi \times 3 = 6\pi.

Adım Adım Çözüm

1
Identify the standard period of the parent cosine function and the coefficient BB of the variable xx in the given function.
The parent function is y=cos⁡(x)y = \cos(x), which has a standard period of 2π2\pi. In the function f(x)=4cos⁡(13x)f(x) = 4\cos\left(\frac{1}{3}x\right), the coefficient of xx is B=13B = \frac{1}{3}.
This sets up the parameters needed for the period formula Period=2π∣B∣\text{Period} = \frac{2\pi}{|B|}.
2
Substitute the value of BB into the period formula and simplify.
The period is 2π13=2π×3=6π\frac{2\pi}{\frac{1}{3}} = 2\pi \times 3 = 6\pi.
Dividing by a fraction is equivalent to multiplying by its reciprocal, which gives the final horizontal distance for one complete cycle.

Anahtar Kavram

Graphs of Trigonometric Functions
Soru 22Soru →

An angle θ\theta in standard position is rotated counterclockwise by 225∘225^\circ. The terminal ray of the resulting angle lies in the fourth quadrant along the line y=−x3y = -x\sqrt{3}. If the radian measure of the smallest positive angle θ\theta is written in simplest form as aπb\frac{a\pi}{b}, where aa and bb are positive integers, what is the value of a+ba + b?

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Cevap: 17

Cevap

The value of a+ba + b is 1717.
The resulting angle α\alpha lies along the line y=−x3y = -x\sqrt{3} in the fourth quadrant, meaning its measure is 300∘300^\circ plus any multiple of 360∘360^\circ. Subtracting the counterclockwise rotation of 225∘225^\circ gives the original angle θ=75∘\theta = 75^\circ (for the smallest positive angle). Converting 75∘75^\circ to radians by multiplying by π180∘\frac{\pi}{180^\circ} yields 5π12\frac{5\pi}{12}. Since the fraction is in simplest form, a=5a = 5 and b=12b = 12, and their sum is 1717.

Adım Adım Çözüm

1
Find the angle of the terminal ray after rotation from its equation and quadrant
The terminal ray after rotation is at an angle of 300∘300^\circ (or 5π3\frac{5\pi}{3} radians)
The line y=−x3y = -x\sqrt{3} has a slope of −3-\sqrt{3}, so the angle α\alpha in Quadrant IV satisfies tan⁡α=−3\tan\alpha = -\sqrt{3}, which means α=300∘\alpha = 300^\circ.
2
Set up and solve the equation for the original angle θ\theta before the counterclockwise rotation of 225∘225^\circ
θ=75∘+360∘k\theta = 75^\circ + 360^\circ k
Since the angle was rotated counterclockwise by 225∘225^\circ to reach the final position of 300∘300^\circ, we have θ+225∘=300∘+360∘k\theta + 225^\circ = 300^\circ + 360^\circ k.
3
Determine the smallest positive value of θ\theta
θ=75∘\theta = 75^\circ
Setting k=0k = 0 gives the smallest positive angle of 75∘75^\circ.
4
Convert the angle θ\theta from degrees to radians
θ=5π12\theta = \frac{5\pi}{12} radians
To convert degrees to radians, multiply by π180∘\frac{\pi}{180^\circ}, yielding 75π180=5π12\frac{75\pi}{180} = \frac{5\pi}{12}.
5
Calculate the sum of the numerator and denominator of the simplified radian fraction
a+b=17a + b = 17
The fraction 512\frac{5}{12} is in simplest form, so a=5a = 5 and b=12b = 12. The sum is 5+12=175 + 12 = 17.

Anahtar Kavram

Converting degree measures to radian measures and finding coterminal angles on the unit circle
Soru 23Soru →

In right triangle PQRPQR, the right angle is at vertex QQ. If the side lengths are PQ=15PQ = 15 and QR=8QR = 8, what is the value of tan⁡(P)\tan(P)?

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Cevap: 815\frac{8}{15}

Cevap

The tangent of angle PP is 815\frac{8}{15}.
The tangent of angle PP is the ratio of the opposite side (QR=8QR = 8) to the adjacent side (PQ=15PQ = 15). This gives the value 815\frac{8}{15}.

Adım Adım Çözüm

1
Identify the reference angle and the sides of the right triangle relative to it.
The reference angle is PP. The side opposite to angle PP is QRQR with a length of 88. The side adjacent to angle PP is PQPQ with a length of 1515. The hypotenuse is PRPR.
To calculate a trigonometric ratio, we must first determine which sides are opposite, adjacent, and the hypotenuse relative to the target angle.
2
Recall the definition of the tangent ratio in a right triangle.
The tangent of an angle is defined as the ratio of the length of the opposite side to the length of the adjacent side: tan⁡(θ)=OppositeAdjacent\tan(\theta) = \frac{\text{Opposite}}{\text{Adjacent}}.
The question asks for the tangent of angle PP.
3
Substitute the identified side lengths into the tangent formula.
tan⁡(P)=QRPQ=815\tan(P) = \frac{QR}{PQ} = \frac{8}{15}.
Plugging the lengths of the opposite side (88) and the adjacent side (1515) into the tangent ratio yields the final value.

Anahtar Kavram

Right triangle trigonometry ratios (SOHCAHTOA), specifically the tangent ratio definition.
Tahmini Süre:45s
Soru 24Soru →

For an angle θ\theta in the interval 3π2<θ<2π\frac{3\pi}{2} < \theta < 2\pi, the expression sec⁡θ−tan⁡θ\sec\theta - \tan\theta is equal to 33. What is the value of csc⁡θ+cot⁡θ\csc\theta + \cot\theta?

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Cevap: -2

Cevap

The value of csc⁡θ+cot⁡θ\csc\theta + \cot\theta is −2-2.
By using the difference of squares on the identity sec⁡2θ−tan⁡2θ=1\sec^2\theta - \tan^2\theta = 1, we get (sec⁡θ−tan⁡θ)(sec⁡θ+tan⁡θ)=1(\sec\theta - \tan\theta)(\sec\theta + \tan\theta) = 1. Substituting sec⁡θ−tan⁡θ=3\sec\theta - \tan\theta = 3 gives sec⁡θ+tan⁡θ=13\sec\theta + \tan\theta = \frac{1}{3}. Solving the system of equations gives sec⁡θ=53\sec\theta = \frac{5}{3} and tan⁡θ=−43\tan\theta = -\frac{4}{3}. Since θ\theta lies in Quadrant IV, cos⁡θ=35\cos\theta = \frac{3}{5} and sin⁡θ=−45\sin\theta = -\frac{4}{5}. We then find csc⁡θ=−54\csc\theta = -\frac{5}{4} and cot⁡θ=−34\cot\theta = -\frac{3}{4}, which sum to −2-2.

Adım Adım Çözüm

1
Use the Pythagorean identity sec⁡2θ−tan⁡2θ=1\sec^2\theta - \tan^2\theta = 1, which factors into (sec⁡θ−tan⁡θ)(sec⁡θ+tan⁡θ)=1(\sec\theta - \tan\theta)(\sec\theta + \tan\theta) = 1.
Since sec⁡θ−tan⁡θ=3\sec\theta - \tan\theta = 3, we have 3(sec⁡θ+tan⁡θ)=1  ⟹  sec⁡θ+tan⁡θ=133(\sec\theta + \tan\theta) = 1 \implies \sec\theta + \tan\theta = \frac{1}{3}.
To establish a second linear equation in terms of sec⁡θ\sec\theta and tan⁡θ\tan\theta.
2
Add and subtract the two equations: sec⁡θ−tan⁡θ=3\sec\theta - \tan\theta = 3 and sec⁡θ+tan⁡θ=13\sec\theta + \tan\theta = \frac{1}{3}.
Adding them gives 2sec⁡θ=103  ⟹  sec⁡θ=532\sec\theta = \frac{10}{3} \implies \sec\theta = \frac{5}{3}. Subtracting the first from the second gives 2tan⁡θ=−83  ⟹  tan⁡θ=−432\tan\theta = -\frac{8}{3} \implies \tan\theta = -\frac{4}{3}.
To isolate the values of sec⁡θ\sec\theta and tan⁡θ\tan\theta.
3
Find cos⁡θ\cos\theta and sin⁡θ\sin\theta using cos⁡θ=1sec⁡θ\cos\theta = \frac{1}{\sec\theta} and sin⁡θ=tan⁡θcos⁡θ\sin\theta = \tan\theta\cos\theta.
cos⁡θ=35\cos\theta = \frac{3}{5} and sin⁡θ=−45\sin\theta = -\frac{4}{5}. Since 3π2<θ<2π\frac{3\pi}{2} < \theta < 2\pi (Quadrant IV), cosine is positive and sine is negative, which matches these values.
To find the primary trigonometric values needed for the reciprocal functions.
4
Calculate csc⁡θ\csc\theta and cot⁡θ\cot\theta using reciprocal identities.
csc⁡θ=1sin⁡θ=−54\csc\theta = \frac{1}{\sin\theta} = -\frac{5}{4} and cot⁡θ=1tan⁡θ=−34\cot\theta = \frac{1}{\tan\theta} = -\frac{3}{4}.
To obtain the terms of the required sum.
5
Sum the values of csc⁡θ\csc\theta and cot⁡θ\cot\theta.
csc⁡θ+cot⁡θ=−54+(−34)=−84=−2\csc\theta + \cot\theta = -\frac{5}{4} + \left(-\frac{3}{4}\right) = -\frac{8}{4} = -2.
To obtain the final value requested by the question.

Anahtar Kavram

Pythagorean and Reciprocal Trigonometric Identities
Soru 25Soru →

For an angle θ\theta such that π<θ<3π2\pi < \theta < \frac{3\pi}{2}, the equation 1−sin⁡θcos⁡θ+cos⁡θ1−sin⁡θ=−103\frac{1 - \sin\theta}{\cos\theta} + \frac{\cos\theta}{1 - \sin\theta} = -\frac{10}{3} is satisfied. What is the value of sin⁡θ\sin\theta?

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Cevap: −45-\frac{4}{5}

Cevap

The value of sin⁡θ\sin\theta is −45-\frac{4}{5}.
The correct answer is determined by first rewriting the given equation by finding a common denominator, which simplifies the numerator to 2(1−sin⁡θ)2(1-\sin\theta) using the Pythagorean identity sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1. The term (1−sin⁡θ)(1-\sin\theta) cancels out, resulting in 2cos⁡θ=−103\frac{2}{\cos\theta} = -\frac{10}{3}, which implies cos⁡θ=−35\cos\theta = -\frac{3}{5}. In Quadrant III, sine is negative, so using the identity sin⁡θ=−1−cos⁡2θ\sin\theta = -\sqrt{1 - \cos^2\theta} yields the correct value.

Adım Adım Çözüm

1
Find a common denominator to add the fractions on the left-hand side of the equation.
The expression becomes (1−sin⁡θ)2+cos⁡2θcos⁡θ(1−sin⁡θ)\frac{(1 - \sin\theta)^2 + \cos^2\theta}{\cos\theta(1 - \sin\theta)}.
To combine the algebraic terms into a single rational expression.
2
Expand the numerator and apply the Pythagorean identity sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1.
The numerator simplifies to 1−2sin⁡θ+sin⁡2θ+cos⁡2θ=1−2sin⁡θ+1=2−2sin⁡θ=2(1−sin⁡θ)1 - 2\sin\theta + \sin^2\theta + \cos^2\theta = 1 - 2\sin\theta + 1 = 2 - 2\sin\theta = 2(1 - \sin\theta).
To reduce the numerator's complexity using fundamental trigonometric identities.
3
Cancel the common factor (1−sin⁡θ)(1 - \sin\theta) from the numerator and denominator, and equate the simplified term to −103-\frac{10}{3}.
The equation simplifies to 2cos⁡θ=−103\frac{2}{\cos\theta} = -\frac{10}{3}, which gives cos⁡θ=−35\cos\theta = -\frac{3}{5}.
To solve for the cosine of the angle θ\theta.
4
Use the Pythagorean identity sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1 to calculate sin⁡θ\sin\theta, keeping the quadrant sign rules in mind.
Since π<θ<3π2\pi < \theta < \frac{3\pi}{2} (Quadrant III), sin⁡θ\sin\theta is negative. Therefore, sin⁡θ=−1−cos⁡2θ=−1−(−35)2=−45\sin\theta = -\sqrt{1 - \cos^2\theta} = -\sqrt{1 - \left(-\frac{3}{5}\right)^2} = -\frac{4}{5}.
To find the correct value and sign of the sine ratio for the given quadrant.

Anahtar Kavram

Fundamental Trigonometric Identities
Soru 26Soru →

Match each of the degree measures of angles in standard position on the left with its mathematically equivalent radian measure on the right. Which radian measure corresponds to each degree measure?

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

−135∘-135^\circ
480∘480^\circ
−300∘-300^\circ
585∘585^\circ

Eşleşmeler

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Cevap

The correct pairings are: −135∘-135^\circ matches with −3π4-\frac{3\pi}{4} radians; 480∘480^\circ matches with 8π3\frac{8\pi}{3} radians; −300∘-300^\circ matches with −5π3-\frac{5\pi}{3} radians; and 585∘585^\circ matches with 13π4\frac{13\pi}{4} radians.
Each degree measure is multiplied by π180∘\frac{\pi}{180^\circ} and simplified to find its equivalent radian measure. This process yields the unique matching pairs: −135∘-135^\circ to −3π4-\frac{3\pi}{4} radians, 480∘480^\circ to 8π3\frac{8\pi}{3} radians, −300∘-300^\circ to −5π3-\frac{5\pi}{3} radians, and 585∘585^\circ to 13π4\frac{13\pi}{4} radians.

Adım Adım Çözüm

1
Recall the formula to convert degrees to radians.
Radian measure = Degree measure ×π180∘\times \frac{\pi}{180^\circ}
Since a full circle is 360∘360^\circ or 2π2\pi radians, the conversion ratio simplifies to π\pi radians per 180∘180^\circ.
2
Convert the first degree measure, −135∘-135^\circ, to radians.
−135∘×π180∘=−135π180=−3π4-135^\circ \times \frac{\pi}{180^\circ} = -\frac{135\pi}{180} = -\frac{3\pi}{4} radians
Dividing the numerator and denominator by their greatest common divisor, 4545, simplifies the fraction to −34-\frac{3}{4}.
3
Convert the second degree measure, 480∘480^\circ, to radians.
480∘×π180∘=480π180=8π3480^\circ \times \frac{\pi}{180^\circ} = \frac{480\pi}{180} = \frac{8\pi}{3} radians
Dividing the numerator and denominator by their greatest common divisor, 6060, simplifies the fraction to 83\frac{8}{3}.
4
Convert the third degree measure, −300∘-300^\circ, to radians.
−300∘×π180∘=−300π180=−5π3-300^\circ \times \frac{\pi}{180^\circ} = -\frac{300\pi}{180} = -\frac{5\pi}{3} radians
Dividing the numerator and denominator by their greatest common divisor, 6060, simplifies the fraction to −53-\frac{5}{3}.
5
Convert the fourth degree measure, 585∘585^\circ, to radians.
585∘×π180∘=585π180=13π4585^\circ \times \frac{\pi}{180^\circ} = \frac{585\pi}{180} = \frac{13\pi}{4} radians
Dividing the numerator and denominator by their greatest common divisor, 4545, simplifies the fraction to 134\frac{13}{4}.

Anahtar Kavram

Converting degree measures to equivalent radian measures using the conversion factor π180∘\frac{\pi}{180^\circ}.

Alternatif Yöntem

Alternatively, you can recall key benchmark angles on the unit circle (such as 45∘=π445^\circ = \frac{\pi}{4} radians and 60∘=π360^\circ = \frac{\pi}{3} radians) and express each angle as an integer multiple of these benchmarks. For example, −135∘-135^\circ is −3×45∘-3 \times 45^\circ, which corresponds to −3×π4=−3π4-3 \times \frac{\pi}{4} = -\frac{3\pi}{4} radians.
Tahmini Süre:1m 30s
Soru 27Soru →

What is the period of the function f(x)=tan⁡(3x)f(x) = \tan(3x)?

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Cevap: π3\frac{\pi}{3}

Cevap

The period of the function is π3\frac{\pi}{3}.
The parent function y=tan⁡(x)y = \tan(x) has a standard period of π\pi. To find the period of a transformed tangent function of the form y=tan⁡(Bx)y = \tan(Bx), the standard period must be divided by the coefficient of xx, yielding π∣B∣\frac{\pi}{|B|}. Substituting B=3B = 3 gives π3\frac{\pi}{3}.

Adım Adım Çözüm

1
Determine the standard period of the parent function.
The parent function is the tangent function, y=tan⁡(x)y = \tan(x), which has a standard period of π\pi.
The tangent function completes one full cycle of its graph between −π2-\frac{\pi}{2} and π2\frac{\pi}{2}.
2
Identify the horizontal compression/stretch coefficient from the given equation.
In f(x)=tan⁡(3x)f(x) = \tan(3x), the coefficient of xx is B=3B = 3.
This coefficient determines how many cycles occur in a standard interval.
3
Calculate the period using the formula for the tangent function.
Period = π∣B∣=π3\frac{\pi}{|B|} = \frac{\pi}{3}.
Dividing the standard period of π\pi by the absolute value of the coefficient BB gives the compressed period of the transformed function.

Anahtar Kavram

The period of a transformed tangent function y=tan⁡(Bx)y = \tan(Bx) is given by π∣B∣\frac{\pi}{|B|}.
Soru 28Soru →

A 1010-foot ladder leans against a vertical wall. The base of the ladder is 66 feet away from the bottom of the wall, and the top of the ladder reaches a height of 88 feet up the wall. If θ\theta is the angle formed between the ladder and the ground, what is the value of cos⁡(θ)\cos(\theta)?

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Cevap: 35\frac{3}{5}

Cevap

The correct answer is 35\frac{3}{5}, which represents the ratio of the adjacent side (66 feet) to the hypotenuse (1010 feet) for the angle θ\theta formed between the ladder and the ground.
The correct answer is the value 35\frac{3}{5}. The angle θ\theta is formed between the ladder (hypotenuse) and the ground (adjacent side). The cosine of an angle in a right triangle is defined as the ratio of the length of the adjacent side to the length of the hypotenuse. Here, the adjacent side is 66 feet and the hypotenuse is 1010 feet. Therefore, cos⁡(θ)=610\cos(\theta) = \frac{6}{10}, which simplifies to 35\frac{3}{5}.

Adım Adım Çözüm

1
Identify the parts of the right triangle relative to the angle θ\theta formed between the ladder and the ground.
The hypotenuse is the length of the ladder (1010 feet). The side adjacent to θ\theta is the distance along the ground from the wall to the base of the ladder (66 feet). The side opposite to θ\theta is the height up the wall (88 feet).
To apply trigonometric ratios, we must first map the given dimensions of the scenario to the sides of a right triangle relative to the reference angle.
2
Recall the definition of the cosine ratio in a right triangle.
cos⁡(θ)=AdjacentHypotenuse\cos(\theta) = \frac{\text{Adjacent}}{\text{Hypotenuse}}
We need to identify the mathematical definition of cosine to set up the calculation.
3
Substitute the identified side lengths into the cosine ratio and simplify the fraction.
cos⁡(θ)=610=35\cos(\theta) = \frac{6}{10} = \frac{3}{5}
Substituting the values of 66 feet for the adjacent side and 1010 feet for the hypotenuse gives 610\frac{6}{10}, which simplifies to 35\frac{3}{5} when both the numerator and denominator are divided by their greatest common divisor, 22.

Anahtar Kavram

Right Triangle Trigonometry (SOHCAHTOA)
Soru 29Soru →

An angle θ\theta lies in the third quadrant, where π<θ<3π2\pi < \theta < \frac{3\pi}{2}. If sin⁡θ−cos⁡θ=−15\sin\theta - \cos\theta = -\frac{1}{5}, what is the value of the expression 125(sin⁡3θ+cos⁡3θ)125(\sin^3\theta + \cos^3\theta)?

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Cevap: -91

Cevap

The correct value of the expression is -91.
Squaring the equation sin⁡θ−cos⁡θ=−15\sin\theta - \cos\theta = -\frac{1}{5} gives 1−2sin⁡θcos⁡θ=1251 - 2\sin\theta\cos\theta = \frac{1}{25}, which simplifies to sin⁡θcos⁡θ=1225\sin\theta\cos\theta = \frac{12}{25}. We then find the square of the sum: (sin⁡θ+cos⁡θ)2=1+2sin⁡θcos⁡θ=1+2425=4925(\sin\theta + \cos\theta)^2 = 1 + 2\sin\theta\cos\theta = 1 + \frac{24}{25} = \frac{49}{25}. Since the angle is in the third quadrant, both trigonometric functions are negative, so we choose the negative root sin⁡θ+cos⁡θ=−75\sin\theta + \cos\theta = -\frac{7}{5}. Factoring the sum of cubes gives sin⁡3θ+cos⁡3θ=(sin⁡θ+cos⁡θ)(sin⁡2θ−sin⁡θcos⁡θ+cos⁡2θ)=(−75)(1−1225)=−91125\sin^3\theta + \cos^3\theta = (\sin\theta + \cos\theta)(\sin^2\theta - \sin\theta\cos\theta + \cos^2\theta) = (-\frac{7}{5})(1 - \frac{12}{25}) = -\frac{91}{125}. Multiplying this by 125 yields -91.

Adım Adım Çözüm

1
Square both sides of the equation sin⁡θ−cos⁡θ=−15\sin\theta - \cos\theta = -\frac{1}{5}
sin⁡2θ−2sin⁡θcos⁡θ+cos⁡2θ=125  ⟹  1−2sin⁡θcos⁡θ=125  ⟹  sin⁡θcos⁡θ=1225\sin^2\theta - 2\sin\theta\cos\theta + \cos^2\theta = \frac{1}{25} \implies 1 - 2\sin\theta\cos\theta = \frac{1}{25} \implies \sin\theta\cos\theta = \frac{12}{25}
To solve for the product of sine and cosine using the Pythagorean identity sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1.
2
Determine the value of sin⁡θ+cos⁡θ\sin\theta + \cos\theta using the identity (sin⁡θ+cos⁡θ)2=1+2sin⁡θcos⁡θ(\sin\theta + \cos\theta)^2 = 1 + 2\sin\theta\cos\theta
(sin⁡θ+cos⁡θ)2=1+2(1225)=4925  ⟹  sin⁡θ+cos⁡θ=−75(\sin\theta + \cos\theta)^2 = 1 + 2(\frac{12}{25}) = \frac{49}{25} \implies \sin\theta + \cos\theta = -\frac{7}{5}
Because θ\theta is in the third quadrant (π<θ<3π2\pi < \theta < \frac{3\pi}{2}), both sin⁡θ\sin\theta and cos⁡θ\cos\theta must be negative, meaning their sum is also negative.
3
Use the sum of cubes factorization to evaluate sin⁡3θ+cos⁡3θ\sin^3\theta + \cos^3\theta
sin⁡3θ+cos⁡3θ=(sin⁡θ+cos⁡θ)(sin⁡2θ−sin⁡θcos⁡θ+cos⁡2θ)=(−75)(1−1225)=−91125\sin^3\theta + \cos^3\theta = (\sin\theta + \cos\theta)(\sin^2\theta - \sin\theta\cos\theta + \cos^2\theta) = (-\frac{7}{5})(1 - \frac{12}{25}) = -\frac{91}{125}
To express the sum of cubes in terms of the known sum and product of sine and cosine.
4
Multiply the evaluated sum of cubes by 125
125×(−91125)=−91125 \times (-\frac{91}{125}) = -91
To compute the final value of the requested expression.

Anahtar Kavram

Pythagorean trigonometric identities, quadrant sign analysis, and algebraic factorization of the sum of cubes

Alternatif Yöntem

Instead of applying algebraic identities to find the sum of cubes directly, we can solve for the individual values of sin⁡θ\sin\theta and cos⁡θ\cos\theta from the system of equations: sin⁡θ−cos⁡θ=−15\sin\theta - \cos\theta = -\frac{1}{5} and sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1. Substituting sin⁡θ=cos⁡θ−15\sin\theta = \cos\theta - \frac{1}{5} into the second equation yields 2cos⁡2θ−25cos⁡θ−2425=02\cos^2\theta - \frac{2}{5}\cos\theta - \frac{24}{25} = 0, which factors as (5cos⁡θ+3)(5cos⁡θ−4)=0(5\cos\theta + 3)(5\cos\theta - 4) = 0. Since θ\theta is in Quadrant III, cos⁡θ=−35\cos\theta = -\frac{3}{5} and sin⁡θ=−45\sin\theta = -\frac{4}{5}. Evaluating 125(sin⁡3θ+cos⁡3θ)125(\sin^3\theta + \cos^3\theta) directly with these values gives 125((−45)3+(−35)3)=125(−64125−27125)=−91125((-\frac{4}{5})^3 + (-\frac{3}{5})^3) = 125(-\frac{64}{125} - \frac{27}{125}) = -91.
Tahmini Süre:2m 30s
Soru 30Soru →

The graph of the function f(x)=acos⁡(b(x−c))+df(x) = a \cos(b(x - c)) + d is shown below for constants a>0a > 0, b>0b > 0, c∈[0,π]c \in [0, \pi], and dd. The graph has a local maximum at (π3,5)(\frac{\pi}{3}, 5) and the nearest local minimum to its right is at (5π6,−1)(\frac{5\pi}{6}, -1). What is the y-intercept of the graph of f(x)f(x)?

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Cevap: 12\frac{1}{2}

Cevap

The y-intercept of the graph is 12\frac{1}{2}
The correct answer is 12\frac{1}{2}. The amplitude of the function is a=5−(−1)2=3a = \frac{5 - (-1)}{2} = 3, and the midline is d=5+(−1)2=2d = \frac{5 + (-1)}{2} = 2. The distance between the consecutive local maximum and local minimum represents half of a period: T2=5π6−π3=π2\frac{T}{2} = \frac{5\pi}{6} - \frac{\pi}{3} = \frac{\pi}{2}, meaning the period is T=πT = \pi, so b=2ππ=2b = \frac{2\pi}{\pi} = 2. A local maximum occurs when the argument of the cosine function is 00, so 2(π3−c)=0  ⟹  c=π32(\frac{\pi}{3} - c) = 0 \implies c = \frac{\pi}{3}. This gives the equation f(x)=3cos⁡(2(x−π3))+2f(x) = 3 \cos(2(x - \frac{\pi}{3})) + 2. Finding the y-intercept requires evaluating the function at x=0x = 0: f(0)=3cos⁡(2(0−π3))+2=3cos⁡(−2π3)+2=3(−12)+2=12f(0) = 3 \cos(2(0 - \frac{\pi}{3})) + 2 = 3 \cos(-\frac{2\pi}{3}) + 2 = 3(-\frac{1}{2}) + 2 = \frac{1}{2}.

Adım Adım Çözüm

1
Find the amplitude aa and midline dd of the trigonometric function.
a=3a = 3 and d=2d = 2
The amplitude is half the distance between the maximum and minimum values: a=5−(−1)2=3a = \frac{5 - (-1)}{2} = 3. The midline is the average of these values: d=5+(−1)2=2d = \frac{5 + (-1)}{2} = 2.
2
Determine the period TT and the frequency coefficient bb.
T=πT = \pi and b=2b = 2
The horizontal distance between a consecutive maximum and minimum is half of the period: 5π6−π3=π2\frac{5\pi}{6} - \frac{\pi}{3} = \frac{\pi}{2}. Thus, the full period is T=πT = \pi. Since T=2πbT = \frac{2\pi}{b}, we find b=2b = 2.
3
Determine the horizontal phase shift cc.
c=π3c = \frac{\pi}{3}
A cosine function achieves its maximum when its argument is a multiple of 2π2\pi. Since the maximum is at x=π3x = \frac{\pi}{3}, we set 2(π3−c)=02(\frac{\pi}{3} - c) = 0, giving c=π3c = \frac{\pi}{3}.
4
Evaluate the function at x=0x = 0 to find the y-intercept.
f(0)=12f(0) = \frac{1}{2}
Substitute the parameters into the function: f(x)=3cos⁡(2(x−π3))+2f(x) = 3 \cos(2(x - \frac{\pi}{3})) + 2. Substituting x=0x = 0 gives f(0)=3cos⁡(−2π3)+2=3(−12)+2=12f(0) = 3 \cos(-\frac{2\pi}{3}) + 2 = 3(-\frac{1}{2}) + 2 = \frac{1}{2}.

Anahtar Kavram

Determining the equation of a transformed trigonometric function from key features (maximum and minimum points) and evaluating it.
Tahmini Süre:3m 0s
Soru 31Soru →

In right triangle ABCABC, the right angle is at vertex BB, AB=12AB = 12, and BC=5BC = 5. A line segment BDBD is drawn perpendicular to the hypotenuse ACAC such that DD lies on ACAC. From point DD, a perpendicular line segment DEDE is drawn to side ABAB, where EE lies on ABAB. What is the length of segment DEDE?

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Cevap: 720169\frac{720}{169}

Cevap

720169\frac{720}{169}
The correct answer is 720169\frac{720}{169}. First, find the hypotenuse of the right triangle ABCABC using the Pythagorean theorem: AC=AB2+BC2=122+52=13AC = \sqrt{AB^2 + BC^2} = \sqrt{12^2 + 5^2} = 13. In right triangle ABCABC, the sine of angle AA is sin⁡(∠A)=BCAC=513\sin(\angle A) = \frac{BC}{AC} = \frac{5}{13}. Next, in right triangle ABDABD (which has a right angle at DD), the length of the altitude BDBD can be found using the sine of angle AA: BD=ABsin⁡(∠A)=12⋅513=6013BD = AB \sin(\angle A) = 12 \cdot \frac{5}{13} = \frac{60}{13}. In right triangle BDEBDE (which has a right angle at EE), the angle ∠BDE\angle BDE is equal to ∠A\angle A because both are complementary to ∠ABD\angle ABD (or ∠EBD\angle EBD). Therefore, the adjacent side DEDE is found using the cosine of angle ∠BDE\angle BDE: DE=BDcos⁡(∠BDE)=BDcos⁡(∠A)=6013⋅1213=720169DE = BD \cos(\angle BDE) = BD \cos(\angle A) = \frac{60}{13} \cdot \frac{12}{13} = \frac{720}{169}.

Adım Adım Çözüm

1
Find the hypotenuse ACAC of the right triangle ABCABC using the Pythagorean theorem.
AC=13AC = 13
The hypotenuse is needed to find the trigonometric ratios of angle AA.
2
Determine sin⁡(∠A)\sin(\angle A) and cos⁡(∠A)\cos(\angle A) from right triangle ABCABC.
sin⁡(∠A)=513\sin(\angle A) = \frac{5}{13} and cos⁡(∠A)=1213\cos(\angle A) = \frac{12}{13}
These trigonometric ratios are needed for the calculations in the nested right triangles.
3
Find the length of altitude BDBD in right triangle ABDABD using sin⁡(∠A)\sin(\angle A).
BD=6013BD = \frac{60}{13}
BDBD serves as the hypotenuse for the next right triangle BDEBDE.
4
Identify that ∠BDE=∠A\angle BDE = \angle A and calculate the length of DEDE in right triangle BDEBDE.
DE=720169DE = \frac{720}{169}
Since ∠BDE=∠A\angle BDE = \angle A, DE=BDcos⁡(∠BDE)=BDcos⁡(∠A)=6013⋅1213=720169DE = BD \cos(\angle BDE) = BD \cos(\angle A) = \frac{60}{13} \cdot \frac{12}{13} = \frac{720}{169}.

Anahtar Kavram

Applying SOHCAHTOA (sine and cosine definitions) sequentially across nested right triangles by identifying equal angles.
Tahmini Süre:2m 0s
Soru 32Soru →

In triangle ABCABC, the length of side aa is 55 centimeters, the length of side bb is 88 centimeters, and the measure of angle CC is 60∘60^\circ. What is the length, in centimeters, of side cc?

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Cevap: 7

Cevap

The length of side cc is 77 centimeters.
Applying the Law of Cosines directly to the given Side-Angle-Side (SAS) triangle yields c2=52+82−2(5)(8)cos⁡60∘=25+64−40=49c^2 = 5^2 + 8^2 - 2(5)(8) \cos 60^\circ = 25 + 64 - 40 = 49, which gives c=7c = 7.

Adım Adım Çözüm

1
Identify the given values and the appropriate formula.
We are given two sides, a=5a = 5 and b=8b = 8, and the included angle C=60∘C = 60^\circ. To find the opposite side cc, we use the Law of Cosines: c2=a2+b2−2abcos⁡Cc^2 = a^2 + b^2 - 2ab \cos C.
The Law of Cosines relates three sides of a triangle to the cosine of one of its angles, which is applicable for Side-Angle-Side (SAS) configurations.
2
Substitute the known values into the Law of Cosines equation.
c2=52+82−2(5)(8)cos⁡60∘c^2 = 5^2 + 8^2 - 2(5)(8) \cos 60^\circ
Plugging the given values into the formula allows us to solve for the unknown side cc.
3
Evaluate the trigonometric and arithmetic terms.
Since cos⁡60∘=0.5\cos 60^\circ = 0.5, we get:
c2=25+64−80(0.5)c^2 = 25 + 64 - 80(0.5)
c2=89−40c^2 = 89 - 40
c2=49c^2 = 49
Simplifying the expression step-by-step leads to the value of c2c^2.
4
Take the square root of both sides to find the side length.
c=49=7c = \sqrt{49} = 7
Since side lengths must be positive, the square root of 4949 gives the exact length of side cc.

Anahtar Kavram

Law of Cosines
Soru 33Soru →

A coordinate grid contains a right triangle, XYZXYZ, with the right angle located at vertex ZZ. The horizontal leg XZXZ has a length of 2424 units, and the vertical leg YZYZ has a length of 77 units. What is the value of cos⁡(X)\cos(X)?

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Cevap: 2425\frac{24}{25}

Cevap

The correct answer is the option representing 2425\frac{24}{25}.
The cosine of an angle in a right triangle is the ratio of the length of the adjacent leg to the length of the hypotenuse. The hypotenuse of the triangle is calculated as 2525 units using the Pythagorean theorem. Relative to angle XX, the adjacent leg is XZ=24XZ = 24 and the hypotenuse is XY=25XY = 25. Therefore, cos⁡(X)=2425\cos(X) = \frac{24}{25}.

Adım Adım Çözüm

1
Use the Pythagorean theorem to calculate the hypotenuse XYXY.
XY=XZ2+YZ2=242+72=576+49=625=25XY = \sqrt{XZ^2 + YZ^2} = \sqrt{24^2 + 7^2} = \sqrt{576 + 49} = \sqrt{625} = 25.
To calculate any primary trigonometric ratio, we need the lengths of the relevant sides, including the hypotenuse.
2
Identify the adjacent side relative to angle XX.
The leg adjacent to angle XX is XZ=24XZ = 24.
Angle XX is formed by the hypotenuse XYXY and the adjacent leg XZXZ.
3
Apply the definition of cosine (adjacent over hypotenuse).
cos⁡(X)=XZXY=2425\cos(X) = \frac{XZ}{XY} = \frac{24}{25}.
By SOHCAHTOA, cosine is the ratio of the adjacent side length to the hypotenuse length.

Anahtar Kavram

Using SOHCAHTOA definitions to find trigonometric ratios in a right triangle.
Tahmini Süre:1m 0s
Soru 34Soru →

For an angle θ\theta such that π2<θ<π\frac{\pi}{2} < \theta < \pi, if cos⁡θ1−sin⁡θ=−3\frac{\cos\theta}{1 - \sin\theta} = -3, what is the value of sin⁡θ−tan⁡θ\sin\theta - \tan\theta?

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Cevap: 3215\frac{32}{15}

Cevap

3215\frac{32}{15}
By multiplying the numerator and denominator of the given expression by 1+sin⁡θ1 + \sin\theta and utilizing the Pythagorean identity sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1, we find that sec⁡θ+tan⁡θ=−3\sec\theta + \tan\theta = -3. Since sec⁡2θ−tan⁡2θ=1\sec^2\theta - \tan^2\theta = 1, it follows that sec⁡θ−tan⁡θ=−13\sec\theta - \tan\theta = -\frac{1}{3}. Solving this system of equations yields sec⁡θ=−53\sec\theta = -\frac{5}{3} (which means cos⁡θ=−35\cos\theta = -\frac{3}{5}) and tan⁡θ=−43\tan\theta = -\frac{4}{3}. In Quadrant II, sine is positive, so sin⁡θ=tan⁡θcos⁡θ=45\sin\theta = \tan\theta \cos\theta = \frac{4}{5}. Thus, sin⁡θ−tan⁡θ=45−(−43)=12+2015=3215\sin\theta - \tan\theta = \frac{4}{5} - \left(-\frac{4}{3}\right) = \frac{12 + 20}{15} = \frac{32}{15}.

Adım Adım Çözüm

1
Multiply the numerator and denominator of the given expression by 1+sin⁡θ1 + \sin\theta to simplify it.
cos⁡θ(1+sin⁡θ)(1−sin⁡θ)(1+sin⁡θ)=−3  ⟹  cos⁡θ(1+sin⁡θ)1−sin⁡2θ=−3\frac{\cos\theta(1 + \sin\theta)}{(1 - \sin\theta)(1 + \sin\theta)} = -3 \implies \frac{\cos\theta(1 + \sin\theta)}{1 - \sin^2\theta} = -3
To set up the Pythagorean identity in the denominator.
2
Substitute the Pythagorean identity 1−sin⁡2θ=cos⁡2θ1 - \sin^2\theta = \cos^2\theta into the denominator.
cos⁡θ(1+sin⁡θ)cos⁡2θ=1+sin⁡θcos⁡θ=sec⁡θ+tan⁡θ=−3\frac{\cos\theta(1 + \sin\theta)}{\cos^2\theta} = \frac{1 + \sin\theta}{\cos\theta} = \sec\theta + \tan\theta = -3
To simplify the expression into basic trigonometric functions.
3
Use the reciprocal identity relationship sec⁡2θ−tan⁡2θ=1\sec^2\theta - \tan^2\theta = 1 to find the difference of secant and tangent.
sec⁡θ−tan⁡θ=1sec⁡θ+tan⁡θ=1−3=−13\sec\theta - \tan\theta = \frac{1}{\sec\theta + \tan\theta} = \frac{1}{-3} = -\frac{1}{3}
To create a system of linear equations for secant and tangent.
4
Solve the system of equations for sec⁡θ\sec\theta and tan⁡θ\tan\theta.
sec⁡θ=−53\sec\theta = -\frac{5}{3} and tan⁡θ=−43\tan\theta = -\frac{4}{3}
Adding the two equations yields 2sec⁡θ=−103  ⟹  sec⁡θ=−532\sec\theta = -\frac{10}{3} \implies \sec\theta = -\frac{5}{3}, and subtracting them yields 2tan⁡θ=−83  ⟹  tan⁡θ=−432\tan\theta = -\frac{8}{3} \implies \tan\theta = -\frac{4}{3}.
5
Find cos⁡θ\cos\theta and sin⁡θ\sin\theta, and calculate the final value of sin⁡θ−tan⁡θ\sin\theta - \tan\theta.
cos⁡θ=−35\cos\theta = -\frac{3}{5}, sin⁡θ=45\sin\theta = \frac{4}{5}, and sin⁡θ−tan⁡θ=45−(−43)=3215\sin\theta - \tan\theta = \frac{4}{5} - \left(-\frac{4}{3}\right) = \frac{32}{15}
Since θ\theta lies in Quadrant II, sine is positive, which is verified by sin⁡θ=tan⁡θ⋅cos⁡θ=(−43)(−35)=45\sin\theta = \tan\theta \cdot \cos\theta = \left(-\frac{4}{3}\right)\left(-\frac{3}{5}\right) = \frac{4}{5}.

Anahtar Kavram

Fundamental Trigonometric Identities
Tahmini Süre:2m 0s
Soru 35Soru →

A straight skateboard ramp has a vertical height of 99 feet and a horizontal length of 1212 feet along the ground. The vertical height and horizontal length meet at a right angle. What is the sine of the angle that the ramp makes with the ground?

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Cevap: 35\frac{3}{5}

Cevap

The value of the sine of the angle is 35\frac{3}{5}.
The sine of an angle in a right triangle is defined as the ratio of the length of the opposite side to the length of the hypotenuse. The opposite side is the vertical height of 99 feet. Using the Pythagorean theorem, the hypotenuse (the length of the ramp) is calculated as 92+122=15\sqrt{9^2 + 12^2} = 15 feet. Therefore, the sine of the angle is 915\frac{9}{15}, which simplifies to 35\frac{3}{5}.

Adım Adım Çözüm

1
Identify the lengths of the legs of the right triangle and calculate the length of the hypotenuse using the Pythagorean theorem.
The hypotenuse (ramp length) is 1515 feet.
The vertical height (99 feet) and horizontal length (1212 feet) form the perpendicular legs of a right triangle. The length of the ramp is the hypotenuse: 92+122=81+144=225=15\sqrt{9^2 + 12^2} = \sqrt{81 + 144} = \sqrt{225} = 15 feet.
2
Identify the opposite side and hypotenuse relative to the angle the ramp makes with the ground, then apply the sine ratio definition.
The sine of the angle is 35\frac{3}{5}.
The angle the ramp makes with the ground is at the bottom vertex. The side opposite this angle is the vertical height (99 feet), and the hypotenuse is the ramp length (1515 feet). The sine ratio is sin⁡(θ)=oppositehypotenuse=915\sin(\theta) = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{9}{15}, which simplifies to 35\frac{3}{5}.

Anahtar Kavram

Right Triangle Trigonometry (SOHCAHTOA)
Tahmini Süre:1m 0s
Soru 36Soru →

A point on the unit circle starts at (1,0)(1, 0) and undergoes a counterclockwise rotation of 570∘570^\circ about the origin. What is the radian measure of the angle in the interval [0,2π)[0, 2\pi) that corresponds to the point's final position?

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Cevap: 7π6\frac{7\pi}{6}

Cevap

The correct answer is the option representing 7π6\frac{7\pi}{6} radians.
The correct answer represents 7π6\frac{7\pi}{6} radians. To find the position on the unit circle after a counterclockwise rotation of 570∘570^\circ, we first determine the coterminal angle within one full rotation (360∘360^\circ). Subtracting 360∘360^\circ from 570∘570^\circ gives 210∘210^\circ. We then convert this angle to radians by multiplying by π180∘\frac{\pi}{180^\circ}, which simplifies to 7π6\frac{7\pi}{6} radians.

Adım Adım Çözüm

1
Find a coterminal angle for 570∘570^\circ within the standard [0∘,360∘)[0^\circ, 360^\circ) range.
570∘−360∘=210∘570^\circ - 360^\circ = 210^\circ
Since a full rotation is 360∘360^\circ, subtracting 360∘360^\circ yields an angle in the same position on the unit circle but within one full rotation.
2
Convert the coterminal angle from degrees to radians by multiplying by π180∘\frac{\pi}{180^\circ}.
210∘×π180∘=210π180=7π6210^\circ \times \frac{\pi}{180^\circ} = \frac{210\pi}{180} = \frac{7\pi}{6} radians
To convert degrees to radians, multiply by the conversion factor π180∘\frac{\pi}{180^\circ}.
3
Verify that the resulting angle is in the interval [0,2π)[0, 2\pi).
Since 0≤7π6<2π0 \le \frac{7\pi}{6} < 2\pi, the angle is in the correct interval.
The question requires the final angle to be in the interval [0,2π)[0, 2\pi).

Anahtar Kavram

Finding coterminal angles and converting degree measures to radian measures on the unit circle.

Alternatif Yöntem

Convert the rotation to radians first: 570∘×π180∘=19π6570^\circ \times \frac{\pi}{180^\circ} = \frac{19\pi}{6} radians. Then, subtract 2π2\pi to find the coterminal angle: 19π6−2π=7π6\frac{19\pi}{6} - 2\pi = \frac{7\pi}{6} radians.
Tahmini Süre:1m 15s
Soru 37Soru →

An angle θ\theta in standard position measures −750∘-750^\circ. Let ϕ\phi be the coterminal angle of θ\theta such that 0≤ϕ<2π0 \le \phi < 2\pi radians. If ϕ=aπb\phi = \frac{a\pi}{b}, where aa and bb are positive integers with no common factors, what is the value of a+ba + b?

Cevabı ve açıklamayı göster

Cevap: 17

Cevap

17
To find the coterminal angle ϕ\phi in the range [0,2π)[0, 2\pi) radians, we first determine the coterminal angle in degrees by adding multiples of 360∘360^\circ. Adding 3×360∘=1080∘3 \times 360^\circ = 1080^\circ to −750∘-750^\circ results in 330∘330^\circ. We then convert 330∘330^\circ to radians by multiplying by π180∘\frac{\pi}{180^\circ}, which simplifies to 11π6\frac{11\pi}{6}. Since 1111 and 66 are positive integers with no common factors, a=11a = 11 and b=6b = 6. The sum a+ba + b is 11+6=1711 + 6 = 17.

Adım Adım Çözüm

1
Find the positive coterminal angle of −750∘-750^\circ within one full rotation.
330∘330^\circ
Adding 1080∘1080^\circ (three full rotations of 360∘360^\circ) to −750∘-750^\circ brings the angle within the standard range of [0∘,360∘)[0^\circ, 360^\circ).
2
Convert the angle from degrees to radians.
11π6\frac{11\pi}{6} radians
Multiplying the degree measure by π180∘\frac{\pi}{180^\circ} and simplifying the fraction converts it to radians.
3
Identify the values of aa and bb and compute their sum.
1717
Comparing 11π6\frac{11\pi}{6} to aπb\frac{a\pi}{b} shows a=11a = 11 and b=6b = 6, which share no common factors. Their sum is 11+6=1711 + 6 = 17.

Anahtar Kavram

Finding coterminal angles and converting angle measures between degrees and radians.
Tahmini Süre:1m 30s
Soru 38Soru →

In triangle PQRPQR, the measure of angle PP is 30∘30^\circ, the measure of angle QQ is 45∘45^\circ, and the length of side QRQR is 1010 units. Which of the following expressions represents the length, in units, of side PRPR?

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Cevap: 10sin⁡(45∘)sin⁡(30∘)\frac{10\sin(45^\circ)}{\sin(30^\circ)}

Cevap

The length of side PRPR is represented by the expression 10sin⁡(45∘)sin⁡(30∘)\frac{10\sin(45^\circ)}{\sin(30^\circ)}.
The correct answer is derived by setting up the Law of Sines proportion: PRsin⁡(45∘)=10sin⁡(30∘)\frac{PR}{\sin(45^\circ)} = \frac{10}{\sin(30^\circ)}. Multiplying both sides by sin⁡(45∘)\sin(45^\circ) yields PR=10sin⁡(45∘)sin⁡(30∘)PR = \frac{10\sin(45^\circ)}{\sin(30^\circ)}.

Adım Adım Çözüm

1
Identify the known values and corresponding angle-side pairs in triangle PQRPQR.
Angle P=30∘P = 30^\circ is opposite to side QR=10QR = 10, and angle Q=45∘Q = 45^\circ is opposite to side PRPR.
This allows us to set up the appropriate trigonometric relationship to solve for the unknown side.
2
Apply the Law of Sines to relate the ratios of the side lengths to the sines of their opposite angles.
PRsin⁡(Q)=QRsin⁡(P)\frac{PR}{\sin(Q)} = \frac{QR}{\sin(P)}, which becomes PRsin⁡(45∘)=10sin⁡(30∘)\frac{PR}{\sin(45^\circ)} = \frac{10}{\sin(30^\circ)}.
The Law of Sines states that the ratio of the length of a side of a triangle to the sine of its opposite angle is constant for all three sides.
3
Isolate the variable representing the length of side PRPR.
PR=10sin⁡(45∘)sin⁡(30∘)PR = \frac{10\sin(45^\circ)}{\sin(30^\circ)}.
Multiply both sides of the equation by sin⁡(45∘)\sin(45^\circ) to solve for PRPR.

Anahtar Kavram

The Law of Sines relates the side lengths of a triangle to the sines of its angles: asin⁡(A)=bsin⁡(B)=csin⁡(C)\frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)}.
Tahmini Süre:1m 0s
Soru 39Soru →

For the trigonometric equations on the left, which description on the right correctly matches the graphical features of each equation?

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

y=−3sin⁡(2x−π3)+1y = -3\sin\left(2x - \frac{\pi}{3}\right) + 1
y=2cos⁡(12x+π4)−1y = 2\cos\left(\frac{1}{2}x + \frac{\pi}{4}\right) - 1
y=−tan⁡(3x−π2)+2y = -\tan\left(3x - \frac{\pi}{2}\right) + 2
y=3sin⁡(23x+π)−2y = 3\sin\left(\frac{2}{3}x + \pi\right) - 2

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

The correct matches are: the equation y=−3sin⁡(2x−π3)+1y = -3\sin\left(2x - \frac{\pi}{3}\right) + 1 matches the description with a period of π\pi, a range of [−2,4][-2, 4], and a positive yy-intercept; the equation y=2cos⁡(12x+π4)−1y = 2\cos\left(\frac{1}{2}x + \frac{\pi}{4}\right) - 1 matches the description with a period of 4π4\pi, a range of [−3,1][-3, 1], and a phase shift of π2\frac{\pi}{2} units to the left; the equation y=−tan⁡(3x−π2)+2y = -\tan\left(3x - \frac{\pi}{2}\right) + 2 matches the description with a period of π3\frac{\pi}{3} that is undefined at the yy-axis; and the equation y=3sin⁡(23x+π)−2y = 3\sin\left(\frac{2}{3}x + \pi\right) - 2 matches the description with a period of 3π3\pi, a range of [−5,1][-5, 1], and a yy-intercept of (0,−2)(0, -2).
Each equation is correctly paired with the unique graphical properties determined by calculating its amplitude, period, range, phase shift, and yy-intercept. The first equation features a period of π\pi, a range of [−2,4][-2, 4], and a positive yy-intercept. The second equation has a period of 4π4\pi, a range of [−3,1][-3, 1], and a phase shift of π2\frac{\pi}{2} units left. The third equation has a period of π3\frac{\pi}{3} and is undefined at the yy-axis since x=0x=0 creates a vertical asymptote. The fourth equation has a period of 3π3\pi, a range of [−5,1][-5, 1], and a yy-intercept of (0,−2)(0, -2).

Adım Adım Çözüm

1
Determine the period, range, and y-intercept for the function y=−3sin⁡(2x−π3)+1y = -3\sin\left(2x - \frac{\pi}{3}\right) + 1.
The period is π\pi, range is [−2,4][-2, 4], and yy-intercept is 1+332>01 + \frac{3\sqrt{3}}{2} > 0.
The period is 2π2=π\frac{2\pi}{2} = \pi, the range is [1−3,1+3]=[−2,4][1-3, 1+3] = [-2, 4], and evaluating at x=0x=0 yields y=−3sin⁡(−π/3)+1>0y = -3\sin(-\pi/3) + 1 > 0.
2
Determine the period, range, and phase shift for the function y=2cos⁡(12x+π4)−1y = 2\cos\left(\frac{1}{2}x + \frac{\pi}{4}\right) - 1.
The period is 4π4\pi, range is [−3,1][-3, 1], and phase shift is π2\frac{\pi}{2} units left.
The period is 2π1/2=4π\frac{2\pi}{1/2} = 4\pi, the range is [−1−2,−1+2]=[−3,1][-1-2, -1+2] = [-3, 1], and factoring the argument yields 12(x+π2)\frac{1}{2}(x + \frac{\pi}{2}), giving a shift of π2\frac{\pi}{2} units left.
3
Determine the period and domain restriction for the function y=−tan⁡(3x−π2)+2y = -\tan\left(3x - \frac{\pi}{2}\right) + 2.
The period is π3\frac{\pi}{3} and the function is undefined at x=0x = 0 (the yy-axis).
For tangent, the period is π3\frac{\pi}{3}. At x=0x=0, the argument is −π2-\frac{\pi}{2}, where tangent is undefined, meaning the function has a vertical asymptote at the yy-axis.
4
Determine the period, range, and y-intercept for the function y=3sin⁡(23x+π)−2y = 3\sin\left(\frac{2}{3}x + \pi\right) - 2.
The period is 3π3\pi, range is [−5,1][-5, 1], and yy-intercept is (0,−2)(0, -2).
The period is 2π2/3=3π\frac{2\pi}{2/3} = 3\pi, the range is [−2−3,−2+3]=[−5,1][-2-3, -2+3] = [-5, 1], and at x=0x=0, y=3sin⁡(π)−2=−2y = 3\sin(\pi) - 2 = -2.

Anahtar Kavram

Identifying graphs of trigonometric functions from their equations by determining amplitude, period, phase shift, midline, range, and asymptotes.
Soru 40Soru →

A surveyor stands at point AA on flat ground and measures the angle of elevation to the top of a vertical tower, TT, at point CC to be 30∘30^\circ. Another surveyor at point BB, which is 100100 meters away from AA on the same flat ground, measures ∠CAB=40∘\angle CAB = 40^\circ and ∠CBA=65∘\angle CBA = 65^\circ. Which of the following expressions represents the height, in meters, of the tower?

Cevabı ve açıklamayı göster

Cevap: 100sin⁡(65∘)tan⁡(30∘)sin⁡(75∘)\frac{100 \sin(65^\circ) \tan(30^\circ)}{\sin(75^\circ)}

Cevap

The correct expression is 100sin⁡(65∘)tan⁡(30∘)sin⁡(75∘)\frac{100 \sin(65^\circ) \tan(30^\circ)}{\sin(75^\circ)}
The correct expression is derived by first applying the Law of Sines to find the length of the ground segment ACAC, and then using right-triangle trigonometry to determine the height of the tower. In triangle ABCABC, the third angle ∠ACB\angle ACB is 180∘−(40∘+65∘)=75∘180^\circ - (40^\circ + 65^\circ) = 75^\circ. The Law of Sines gives ACsin⁡(65∘)=100sin⁡(75∘)\frac{AC}{\sin(65^\circ)} = \frac{100}{\sin(75^\circ)}, which simplifies to AC=100sin⁡(65∘)sin⁡(75∘)AC = \frac{100\sin(65^\circ)}{\sin(75^\circ)}. Since the tower is vertical, triangle ACTACT is a right triangle with tan⁡(30∘)=hAC\tan(30^\circ) = \frac{h}{AC}. Substituting ACAC yields h=100sin⁡(65∘)tan⁡(30∘)sin⁡(75∘)h = \frac{100\sin(65^\circ)\tan(30^\circ)}{\sin(75^\circ)}.

Adım Adım Çözüm

1
Calculate the measure of the third angle in the ground triangle △ABC\triangle ABC.
∠ACB=180∘−(40∘+65∘)=75∘\angle ACB = 180^\circ - (40^\circ + 65^\circ) = 75^\circ
The sum of angles in any triangle must equal 180∘180^\circ.
2
Apply the Law of Sines to find the distance from point AA to the base of the tower at point CC (ACAC).
ACsin⁡(65∘)=100sin⁡(75∘)⇒AC=100sin⁡(65∘)sin⁡(75∘)\frac{AC}{\sin(65^\circ)} = \frac{100}{\sin(75^\circ)} \Rightarrow AC = \frac{100 \sin(65^\circ)}{\sin(75^\circ)}
The Law of Sines states that the ratio of a side length to the sine of its opposite angle is constant in a triangle.
3
Use the right-triangle trigonometric ratio for the vertical tower height hh from point AA.
tan⁡(30∘)=hAC⇒h=ACtan⁡(30∘)\tan(30^\circ) = \frac{h}{AC} \Rightarrow h = AC \tan(30^\circ)
In right triangle △ACT\triangle ACT, the tangent of the angle of elevation is the ratio of the opposite side (height hh) to the adjacent side (ACAC).
4
Substitute the expression for ACAC into the equation for hh.
h=100sin⁡(65∘)tan⁡(30∘)sin⁡(75∘)h = \frac{100 \sin(65^\circ) \tan(30^\circ)}{\sin(75^\circ)}
Replacing ACAC with its equivalent algebraic expression yields the final height in terms of the given parameters.

Anahtar Kavram

Applying the Law of Sines to find a missing side length in a non-right triangle and then using right-triangle trigonometric ratios to solve a 3D geometry problem.
Tahmini Süre:2m 0s
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Trigonometry Alıştırma Soruları — ACT — Sayfa 2 | Examkin