Geometry

156 soru

Soru 1Soru

Sector S1S_1 belongs to a circle with radius rr and has a central angle of measure θ\theta^\circ, where 0<θ<3600 < \theta < 360. Sector S2S_2 belongs to a circle with radius 2r2r and has a central angle of measure (θ2)\left(\frac{\theta}{2}\right)^\circ. Which of the following statements must be true? Select all such statements.

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Cevap: The area of sector S2S_2 is twice the area of sector S1S_1.; The arc length of sector S2S_2 is equal to the arc length of sector S1S_1.; The ratio of the area of sector S1S_1 to its arc length is half the ratio of the area of sector S2S_2 to its arc length.

Cevap

The true statements are that the area of sector S2S_2 is twice the area of sector S1S_1, the arc length of sector S2S_2 is equal to the arc length of sector S1S_1, and the ratio of area to arc length for sector S1S_1 is half that of sector S2S_2.
The area of sector S2S_2 is twice that of S1S_1 because quadrupling r2r^2 combined with halving the central angle results in a factor of 2. The arc length of sector S2S_2 equals that of S1S_1 because doubling rr and halving the angle cancel each other out. The area-to-arc-length ratio of any sector reduces to R2\frac{R}{2}, so sector S1S_1 with radius rr has ratio r2\frac{r}{2}, which is half the ratio rr of sector S2S_2.

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1
Calculate and compare the sector areas.
Area(S1)=θ360πr2\text{Area}(S_1) = \frac{\theta}{360}\pi r^2 and Area(S2)=θ/2360π(2r)2=θ720π(4r2)=2θ360πr2=2Area(S1)\text{Area}(S_2) = \frac{\theta/2}{360}\pi (2r)^2 = \frac{\theta}{720}\pi (4r^2) = \frac{2\theta}{360}\pi r^2 = 2 \cdot \text{Area}(S_1).
The sector area formula is Area=angle360πR2\text{Area} = \frac{\text{angle}}{360^\circ} \pi R^2. Doubling the radius quadruples R2R^2, while halving the angle reduces the fraction by half, producing a net doubling of area.
2
Calculate and compare the arc lengths.
Arc(S1)=θ360(2πr)\text{Arc}(S_1) = \frac{\theta}{360}(2\pi r) and Arc(S2)=θ/2360(2π2r)=θ360(2πr)=Arc(S1)\text{Arc}(S_2) = \frac{\theta/2}{360}(2\pi \cdot 2r) = \frac{\theta}{360}(2\pi r) = \text{Arc}(S_1).
The arc length formula is Arc=angle360(2πR)\text{Arc} = \frac{\text{angle}}{360^\circ} (2\pi R). Doubling the radius doubles RR, while halving the angle halves the fraction, leaving the product unchanged.
3
Calculate and compare the sector perimeters.
Perimeter(S1)=2r+Arc(S1)\text{Perimeter}(S_1) = 2r + \text{Arc}(S_1) and Perimeter(S2)=4r+Arc(S2)=4r+Arc(S1)\text{Perimeter}(S_2) = 4r + \text{Arc}(S_2) = 4r + \text{Arc}(S_1).
The perimeter of a sector consists of two straight radii and the curved arc length. 2Perimeter(S1)=4r+2Arc(S1)Perimeter(S2)2 \cdot \text{Perimeter}(S_1) = 4r + 2\text{Arc}(S_1) \neq \text{Perimeter}(S_2).
4
Evaluate the area-to-arc-length ratios for both sectors.
For S1S_1, Area(S1)Arc(S1)=θ360πr2θ3602πr=r2\frac{\text{Area}(S_1)}{\text{Arc}(S_1)} = \frac{\frac{\theta}{360}\pi r^2}{\frac{\theta}{360}2\pi r} = \frac{r}{2}. For S2S_2, Area(S2)Arc(S2)=2r2=r\frac{\text{Area}(S_2)}{\text{Arc}(S_2)} = \frac{2r}{2} = r.
The ratio of area to arc length simplifies to R2\frac{R}{2} for any sector, so doubling the radius doubles this ratio.

Anahtar Kavram

Geometric properties of circle sectors, including proportional relationships between radius, central angle, arc length, sector area, and total sector perimeter.
Tahmini Süre:2m 0s
Soru 2Soru

In circle OO, sector AOBAOB has a central angle of 6060^\circ and a radius of 1212. A smaller circle CC is inscribed within sector AOBAOB such that it is tangent to radii OAOA and OBOB, as well as to arc ABAB. What is the area of the region inside sector AOBAOB that lies outside circle CC?

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Cevap: 8π8\pi

Cevap

The area of the region inside sector AOBAOB outside circle CC is 8π8\pi.
The correct answer is derived by first finding the area of sector AOBAOB using 60360π(122)=24π\frac{60}{360} \pi (12^2) = 24\pi. Then, analyzing the geometry of the inscribed circle reveals that the line from OO to the center of circle CC bisects the 6060^\circ angle. In the resulting 30609030^\circ-60^\circ-90^\circ right triangle, the hypotenuse length is 2r2r, making the total radius of sector AOBAOB equal to 2r+r=3r=122r + r = 3r = 12, which yields r=4r = 4. The area of circle CC is π(42)=16π\pi (4^2) = 16\pi. Subtracting the circle area from the sector area gives 24π16π=8π24\pi - 16\pi = 8\pi.

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1
Calculate the area of sector AOBAOB
Sector area =60360×π(122)=16×144π=24π= \frac{60^\circ}{360^\circ} \times \pi (12^2) = \frac{1}{6} \times 144\pi = 24\pi
The area of a sector with central angle θ\theta and radius RR is θ360πR2\frac{\theta}{360^\circ} \pi R^2.
2
Find the radius rr of the inscribed circle CC
Distance from OO to center of circle CC is OP=2rOP = 2r, so total radius R=OP+r=3r=12    r=4R = OP + r = 3r = 12 \implies r = 4
The line segment connecting center OO to center PP of circle CC bisects the 6060^\circ angle into two 3030^\circ angles. A perpendicular dropped from PP to radius OAOA forms a 30609030^\circ-60^\circ-90^\circ right triangle where sin(30)=rOP=12\sin(30^\circ) = \frac{r}{OP} = \frac{1}{2}, giving OP=2rOP = 2r.
3
Calculate the area of circle CC
Area of circle C=πr2=π(42)=16πC = \pi r^2 = \pi (4^2) = 16\pi
The area of a circle with radius rr is πr2\pi r^2.
4
Subtract the area of circle CC from the area of sector AOBAOB
24π16π=8π24\pi - 16\pi = 8\pi
The desired region is the difference between the full sector area and the enclosed circle's area.

Anahtar Kavram

Inscribed circles in sectors and central angle sector area calculations
Tahmini Süre:2m 30s
Soru 3Soru

An equilateral triangle ABCABC with side length 636\sqrt{3} is inscribed in a circle with center OO. What is the area of sector AOBAOB, divided by π\pi?

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Cevap: 12

Cevap

The area of sector AOBAOB divided by π\pi is 12.
Since triangle ABCABC is equilateral, its three vertices divide the circle into three congruent arcs of 120120^\circ each. Thus, central angle AOB=120\angle AOB = 120^\circ. The relationship between the side length ss of an inscribed equilateral triangle and the radius RR of its circumscribed circle is s=R3s = R\sqrt{3}. Given s=63s = 6\sqrt{3}, we solve for RR to find R=6R = 6. The area of sector AOBAOB is 120360πR2=13π(62)=12π\frac{120^\circ}{360^\circ} \pi R^2 = \frac{1}{3} \pi (6^2) = 12\pi. Dividing this area by π\pi yields 1212.

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1
Find the central angle AOB\angle AOB corresponding to side ABAB of the inscribed equilateral triangle.
AOB=120\angle AOB = 120^\circ
An inscribed equilateral triangle divides the 360360^\circ circle into three equal central angles.
2
Calculate the radius RR of the circumscribed circle from the given side length s=63s = 6\sqrt{3}.
R=6R = 6
In an inscribed equilateral triangle, s=R3s = R\sqrt{3}. Substituting 63=R36\sqrt{3} = R\sqrt{3} gives R=6R = 6.
3
Compute the area of sector AOBAOB and divide by π\pi.
12
Sector Area=120360×π×62=12π\text{Sector Area} = \frac{120^\circ}{360^\circ} \times \pi \times 6^2 = 12\pi. Dividing by π\pi leaves 1212.

Anahtar Kavram

Relationship between inscribed shapes, circle radii, and sector area
Soru 4Soru

A right circular cylinder has base radius rr and height hh. The height of the cylinder is increased by 50%50\%, and its base radius is decreased by 20%20\%. Which of the following statements about the modified cylinder compared to the original cylinder must be true? Select all that apply.

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Cevap: The volume of the cylinder decreases by 4%4\%.; The lateral surface area of the cylinder increases by 20%20\%.; If h=rh = r, the total surface area of the cylinder decreases.

Cevap

The statements confirming a 4%4\% volume decrease, a 20%20\% lateral surface area increase, and a total surface area decrease when h=rh = r are all true.
The volume of the modified cylinder decreases by 4%4\% because 0.82×1.5=0.960.8^2 \times 1.5 = 0.96. The lateral surface area increases by 20%20\% because 0.8×1.5=1.200.8 \times 1.5 = 1.20. When h=rh = r, the original total surface area 4πr24\pi r^2 reduces to 3.68πr23.68\pi r^2, confirming a decrease.

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1
Express original and modified dimensions algebraically.
Original: radius =r= r, height =h= h. Modified: radius =0.8r= 0.8r, height =1.5h= 1.5h.
Decreasing radius by 20%20\% multiplies it by 10.20=0.801 - 0.20 = 0.80, while increasing height by 50%50\% multiplies it by 1+0.50=1.501 + 0.50 = 1.50.
2
Calculate the ratio of modified volume to original volume.
Vnew=π(0.8r)2(1.5h)=0.64×1.5πr2h=0.96VoldV_{new} = \pi (0.8r)^2 (1.5h) = 0.64 \times 1.5 \pi r^2 h = 0.96 V_{old}, indicating a 4%4\% volume decrease.
Volume of a cylinder is given by V=πr2hV = \pi r^2 h.
3
Calculate the ratio of modified lateral surface area to original lateral surface area.
Lnew=2π(0.8r)(1.5h)=2.4πrh=1.20LoldL_{new} = 2\pi (0.8r)(1.5h) = 2.4\pi r h = 1.20 L_{old}, indicating a 20%20\% lateral surface area increase.
Lateral surface area of a cylinder is given by L=2πrhL = 2\pi r h.
4
Evaluate the base area change and total surface area under specific height-to-radius ratios.
Base area becomes (0.8)2=0.64(0.8)^2 = 0.64 of original (36%36\% decrease). For h=rh = r, total surface area changes from 4πr24\pi r^2 to 3.68πr23.68\pi r^2 (decrease). For h=4rh = 4r, total surface area changes from 10πr210\pi r^2 to 10.88πr210.88\pi r^2 (increase).
Total surface area is the sum of lateral surface area and base area, A=2πr2+2πrhA = 2\pi r^2 + 2\pi r h.

Anahtar Kavram

Impact of dimensional scaling on volume, lateral surface area, and total surface area of cylinders
Soru 5Soru

A vertical flagpole stands on flat, horizontal ground. An observer at point SS on the ground measures the angle of elevation to the top of the flagpole to be 6060^\circ. A second observer at point PP on the ground, located 3030 feet further from the base of the flagpole along the same line extending from the base through SS, measures the angle of elevation to the top of the flagpole to be 3030^\circ. What is the height of the flagpole, in feet?

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Cevap: 15315\sqrt{3}

Cevap

The height of the flagpole is 15315\sqrt{3} feet.
Let BB be the base and TT be the top of the flagpole. The right triangle TBSTBS has angles 3030^\circ, 6060^\circ, and 9090^\circ at BB. If BS=xBS = x, then the height TB=x3TB = x\sqrt{3}. In right triangle TBPTBP, the angle at PP is 3030^\circ, so the base BP=TB3=(x3)3=3xBP = TB\sqrt{3} = (x\sqrt{3})\sqrt{3} = 3x. Since BP=BS+30BP = BS + 30, we set up 3x=x+303x = x + 30, yielding x=15x = 15. Therefore, the height TB=153TB = 15\sqrt{3} feet.

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1
Model the scenario using right triangles.
Let BB be the base of the flagpole and TT be the top. Triangle TBSTBS is a 30609030^\circ-60^\circ-90^\circ right triangle at BB, and triangle TBPTBP is also a 30609030^\circ-60^\circ-90^\circ right triangle at BB.
The flagpole is perpendicular to the horizontal ground.
2
Express side lengths in terms of base distance x=BSx = BS.
In 30609030^\circ-60^\circ-90^\circ triangle TBSTBS, TB=x3TB = x\sqrt{3} and ST=2xST = 2x.
The side opposite the 6060^\circ angle is 3\sqrt{3} times the side opposite the 3030^\circ angle.
3
Set up the equation for triangle TBPTBP.
In 30609030^\circ-60^\circ-90^\circ triangle TBPTBP, the side opposite the 3030^\circ angle is TB=x3TB = x\sqrt{3}, so the adjacent side BP=(x3)3=3xBP = (x\sqrt{3})\sqrt{3} = 3x.
The side opposite the 6060^\circ angle (BPBP) is 3\sqrt{3} times the side opposite the 3030^\circ angle (TBTB).
4
Solve for xx using the given distance SP=30SP = 30.
Since BP=BS+SPBP = BS + SP, we have 3x=x+303x = x + 30, which simplifies to 2x=302x = 30, so x=15x = 15.
The total horizontal distance BPBP is the sum of segments BSBS and SPSP.
5
Calculate the height TBTB.
TB=153TB = 15\sqrt{3}.
Substitute x=15x = 15 into TB=x3TB = x\sqrt{3}.

Anahtar Kavram

Special Right Triangle Ratios (30609030^\circ-60^\circ-90^\circ)
Tahmini Süre:1m 30s
Soru 6Soru

In convex quadrilateral ABCDABCD, diagonal ACAC is drawn. It is given that AB=9AB = 9, BC=12BC = 12, CD=8CD = 8, and DA=15DA = 15, with ABC=90\angle ABC = 90^\circ. Which of the following statements must be true? Select all that apply.

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Cevap: The length of diagonal ACAC is 15.; The perimeter of quadrilateral ABCDABCD is 44.; The sum of the interior angles of quadrilateral ABCDABCD is 360360^\circ.

Cevap

The correct statements are that the length of diagonal ACAC is 15, the perimeter of quadrilateral ABCDABCD is 44, and the sum of the interior angles of quadrilateral ABCDABCD is 360360^\circ.
The statement specifying that the length of diagonal ACAC is 15 is correct because right triangle ABCABC has leg lengths 9 and 12, giving hypotenuse 81+144=15\sqrt{81 + 144} = 15. The statement specifying that the perimeter is 44 is correct because summing the outer side lengths yields 9+12+8+15=449 + 12 + 8 + 15 = 44. The statement specifying that the interior angle sum is 360360^\circ is correct because every convex quadrilateral has an interior angle sum of (42)×180=360(4 - 2) \times 180^\circ = 360^\circ.

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1
Calculate the length of diagonal ACAC using triangle ABCABC.
AC=AB2+BC2=92+122=15AC = \sqrt{AB^2 + BC^2} = \sqrt{9^2 + 12^2} = 15.
Since ABC=90\angle ABC = 90^\circ, triangle ABCABC is a right triangle, allowing the application of the Pythagorean theorem.
2
Calculate the perimeter of quadrilateral ABCDABCD.
Perimeter =9+12+8+15=44= 9 + 12 + 8 + 15 = 44.
The perimeter of a polygon is the sum of all its outer side lengths.
3
Verify the sum of the interior angles for quadrilateral ABCDABCD.
Interior angle sum =(42)×180=360= (4 - 2) \times 180^\circ = 360^\circ.
The formula (n2)×180(n - 2) \times 180^\circ applies to all convex polygons.
4
Evaluate the incorrect claims regarding area and triangle formation.
Triangle ADCADC is not a right triangle (82+1521528^2 + 15^2 \neq 15^2), so its area is not 60; and side lengths 8, 15, and 32 violate the triangle inequality theorem (8+15=23<328 + 15 = 23 < 32).
Right triangle formulas require a right angle, and valid triangle side lengths must satisfy the triangle inequality theorem.

Anahtar Kavram

Properties of convex quadrilaterals, right triangle side relationships, and triangle inequality bounds
Tahmini Süre:1m 30s
Soru 7Soru

In the plane, line L1L_1 is parallel to line L2L_2. A transversal line TT intersects L1L_1 and L2L_2. One of the acute angles formed at the intersection of L1L_1 and TT measures (4x10)(4x - 10)^\circ, and an alternate interior angle on L2L_2 measures (2x+30)(2x + 30)^\circ. What is the degree measure of one of the obtuse angles formed at the intersection of L1L_1 and TT?

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Cevap: 110110^\circ

Cevap

The degree measure of the obtuse angle is 110110^\circ.
Since lines L1L_1 and L2L_2 are parallel, alternate interior angles are equal in measure. Setting (4x10)=(2x+30)(4x - 10)^\circ = (2x + 30)^\circ gives 2x=402x = 40, so x=20x = 20. Substituting x=20x = 20 into 4x104x - 10 gives an acute angle of 7070^\circ. Because angles on a straight line are supplementary, the obtuse angle measures 18070=110180^\circ - 70^\circ = 110^\circ, which corresponds to the correct choice.

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1
Set alternate interior angles equal to solve for xx.
4x10=2x+30    2x=40    x=204x - 10 = 2x + 30 \implies 2x = 40 \implies x = 20
When two parallel lines are cut by a transversal, alternate interior angles are congruent.
2
Substitute x=20x = 20 into the expression for the acute angle.
Acute angle =4(20)10=70= 4(20) - 10 = 70^\circ
This yields the degree measure of the acute angle formed by the intersection.
3
Calculate the measure of the supplementary obtuse angle.
Obtuse angle =18070=110= 180^\circ - 70^\circ = 110^\circ
Adjacent angles along a straight line are supplementary and sum to 180180^\circ.

Anahtar Kavram

Alternate Interior Angles and Supplementary Angles
Tahmini Süre:50s
Soru 8Soru

In triangle ABCABC, the length of side ABAB is 1515 and the length of side BCBC is 2525. The area of triangle ABCABC is 150150. If angle ABCABC is obtuse, what is the length of side ACAC?

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Cevap: 101310\sqrt{13}

Cevap

101310\sqrt{13}
The correct answer 101310\sqrt{13} is obtained by drawing altitude AH=12AH = 12 to line BCBC. In right triangle ABHABH, the base projection is BH=152122=9BH = \sqrt{15^2 - 12^2} = 9. Because angle ABCABC is obtuse, point HH lies outside segment BCBC, so CH=25+9=34CH = 25 + 9 = 34. Applying the Pythagorean theorem to right triangle AHCAHC gives AC=122+342=1300=1013AC = \sqrt{12^2 + 34^2} = \sqrt{1300} = 10\sqrt{13}.

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1
Calculate the height (altitude) hh perpendicular to line BCBC.
Since Area=12×base×height\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}, we have 150=12×25×h150 = \frac{1}{2} \times 25 \times h, which simplifies to h=12h = 12.
The area formula for any triangle connects the base length and its corresponding perpendicular altitude.
2
Determine the location of the altitude foot HH and calculate segment BHBH.
Draw altitude AHAH to the line containing BCBC. In right triangle ABHABH, AB=15AB = 15 and AH=12AH = 12, so BH=152122=225144=81=9BH = \sqrt{15^2 - 12^2} = \sqrt{225 - 144} = \sqrt{81} = 9.
The Pythagorean theorem applies to right triangle ABHABH formed by the altitude.
3
Account for the obtuse angle condition to find segment CHCH.
Because angle ABCABC is obtuse, the altitude foot HH lies on the extension of segment CBCB beyond vertex BB. Therefore, CH=CB+BH=25+9=34CH = CB + BH = 25 + 9 = 34.
For an obtuse triangle, the altitude to one of the adjacent sides falls outside the triangle.
4
Calculate side length ACAC using right triangle AHCAHC.
AC=AH2+CH2=122+342=144+1156=1300=1013AC = \sqrt{AH^2 + CH^2} = \sqrt{12^2 + 34^2} = \sqrt{144 + 1156} = \sqrt{1300} = 10\sqrt{13}.
Applying the Pythagorean theorem to right triangle AHCAHC yields the hypotenuse ACAC.

Anahtar Kavram

Triangle Area, Altitude Projection, and Extended Pythagorean Theorem
Soru 9Soru

A triangle has a base of length 1010 and an area of 3030. Which of the following statements could be true about this triangle? Select all that apply.

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Cevap: The altitude corresponding to the base of length 1010 is 66.; The triangle is a right triangle.; The perimeter of the triangle is 3030.

Cevap

The altitude perpendicular to the given base must be 6, the triangle can be a right triangle, and the perimeter can be equal to 30.
The area formula directly forces the altitude to be 6. Setting the altitude at one endpoint of the base constructs a valid right triangle. Furthermore, the minimum perimeter of any triangle with base 10 and height 6 is 10+26125.6210 + 2\sqrt{61} \approx 25.62, so any perimeter value greater than or equal to 25.6225.62 (such as 30) is attainable.

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1
Calculate the required altitude of the triangle.
Using Area=12×base×h\text{Area} = \frac{1}{2} \times \text{base} \times h, 30=12(10)h    h=630 = \frac{1}{2}(10)h \implies h = 6.
The area and base are fixed, determining a unique height.
2
Evaluate whether the triangle can be a right triangle.
A right triangle with legs 1010 and 66 has area 12×10×6=30\frac{1}{2} \times 10 \times 6 = 30.
Choosing the altitude to meet the base at an endpoint creates a right angle.
3
Determine the lower bound for the perimeter of the triangle.
The third vertex lies on a line parallel to the base at a distance of 66. By symmetry, the minimum sum of the remaining two sides occurs when the triangle is isosceles with base 1010 split into two segments of length 55. Each equal side is 52+62=617.8102\sqrt{5^2 + 6^2} = \sqrt{61} \approx 7.8102. The minimum perimeter is 10+26125.6210 + 2\sqrt{61} \approx 25.62.
The shortest path from two fixed base endpoints to a parallel line is formed when the reflection creates equal angles, making the triangle isosceles.
4
Assess the possible perimeter values based on the lower bound.
Perimeters 2222 and 2424 are strictly below the minimum boundary of 25.62\approx 25.62 and are impossible. Since the perimeter can take any value in [10+261,)[10 + 2\sqrt{61}, \infty), a perimeter of 3030 is possible.
Continuous movement of the top vertex increases the side lengths smoothly without bound.

Anahtar Kavram

Triangle area formula Area=12bh\text{Area} = \frac{1}{2}bh and geometric optimization of perimeter for a given base and height.
Soru 10Soru

In the xyxy-plane, line kk passes through the points (1,2)(1, -2) and (5,6)(5, 6). Line mm is the perpendicular bisector of the line segment connecting (1,2)(1, -2) and (5,6)(5, 6). Which of the following statements must be true? Select all that apply.

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Cevap: Line mm passes through the point (7,0)(7, 0).; Line mm has a yy-intercept of (0,3.5)(0, 3.5).; The distance from the origin (0,0)(0, 0) to the midpoint of the line segment is 13\sqrt{13}.

Cevap

The statements asserting that line mm passes through (7,0)(7, 0), that line mm has a yy-intercept of (0,3.5)(0, 3.5), and that the distance from the origin to the midpoint of the segment is 13\sqrt{13} are all true.
Line kk has slope 6(2)51=2\frac{6 - (-2)}{5 - 1} = 2 and segment midpoint (3,2)(3, 2). Line mm, as the perpendicular bisector, has slope 12-\frac{1}{2} and equation y=12x+3.5y = -\frac{1}{2}x + 3.5. Substituting x=7x = 7 gives y=0y = 0, so (7,0)(7, 0) lies on line mm. Substituting x=0x = 0 gives y=3.5y = 3.5, confirming the yy-intercept. Finally, the distance from (0,0)(0,0) to the midpoint (3,2)(3,2) is 32+22=13\sqrt{3^2 + 2^2} = \sqrt{13}. Thus, all three of these statements are correct.

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1
Find the midpoint and slope of the segment connecting (1,2)(1, -2) and (5,6)(5, 6).
Midpoint M=(1+52,2+62)=(3,2)M = \left(\frac{1+5}{2}, \frac{-2+6}{2}\right) = (3, 2). Slope of segment mk=6(2)51=84=2m_k = \frac{6 - (-2)}{5 - 1} = \frac{8}{4} = 2.
Line mm is the perpendicular bisector, so it passes through midpoint MM and has a slope perpendicular to mkm_k.
2
Determine the slope and equation of line mm.
Perpendicular slope mm=1mk=12m_m = -\frac{1}{m_k} = -\frac{1}{2}. Point-slope equation through (3,2)(3, 2): y2=12(x3)    y=12x+72y - 2 = -\frac{1}{2}(x - 3) \implies y = -\frac{1}{2}x + \frac{7}{2}.
Perpendicular lines have negative reciprocal slopes.
3
Evaluate each given statement against the calculated values.
Line mm contains (7,0)(7, 0) because 0=12(7)+720 = -\frac{1}{2}(7) + \frac{7}{2}. The yy-intercept is (0,3.5)(0, 3.5). Distance from (0,0)(0,0) to (3,2)(3,2) is 32+22=13\sqrt{3^2 + 2^2} = \sqrt{13}. Statements claiming slope is 22 or that line mm is parallel to 2xy=42x - y = 4 are incorrect.
Determines which statements satisfy all mathematical conditions.

Anahtar Kavram

Perpendicular Bisectors, Slopes of Perpendicular Lines, and Distance Formula
Soru 11Soru

In regular octagon ABCDEFGHABCDEFGH with side length 22, diagonals ADAD and BEBE intersect at point PP. What is the area of quadrilateral ABCPABCP?

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Cevap: 2+22 + \sqrt{2}

Cevap

2+22 + \sqrt{2}
In regular octagon ABCDEFGHABCDEFGH, each interior angle measures 135135^\circ. Segment ABCDABCD forms an isosceles trapezoid where ADAD is parallel to BCBC. The perpendicular distance from ADAD to BCBC is 2sin(45)=22 \sin(45^\circ) = \sqrt{2}, and AD=2+2(2cos(45))=2+22AD = 2 + 2(2 \cos(45^\circ)) = 2 + 2\sqrt{2}. Diagonal BEBE is parallel to side CDCD, so CBE=45\angle CBE = 45^\circ, which implies ABE=13545=90\angle ABE = 135^\circ - 45^\circ = 90^\circ. Triangle ABP\triangle ABP is therefore a right isosceles triangle with legs AB=2AB = 2 and BP=2BP = 2, yielding hypotenuse AP=22AP = 2\sqrt{2}. Quadrilateral ABCPABCP is a trapezoid with parallel sides BC=2BC = 2 and AP=22AP = 2\sqrt{2} and height h=2h = \sqrt{2}. Its area is 2+222×2=2+2\frac{2 + 2\sqrt{2}}{2} \times \sqrt{2} = 2 + \sqrt{2}.

Adım Adım Çözüm

1
Calculate the interior angle of a regular octagon
Interior angle = (82)×1808=135\frac{(8-2) \times 180^\circ}{8} = 135^\circ
Regular polygon interior angle formula.
2
Determine the orientation and length of diagonal ADAD
ADBCAD \parallel BC, height between them is h=2sin(45)=2h = 2 \sin(45^\circ) = \sqrt{2}, and base AD=2+2(2cos(45))=2+22AD = 2 + 2(2 \cos(45^\circ)) = 2 + 2\sqrt{2}
Quadrilateral ABCDABCD forms an isosceles trapezoid with side length 22 and interior angles 135135^\circ.
3
Determine the direction of diagonal BEBE and find intersection point PP
CBE=180135=45\angle CBE = 180^\circ - 135^\circ = 45^\circ, making ABE=13545=90\angle ABE = 135^\circ - 45^\circ = 90^\circ
Quadrilateral BCDEBCDE is an isosceles trapezoid with BECDBE \parallel CD.
4
Calculate the dimensions of right triangle ABP\triangle ABP and segment APAP
ABP\triangle ABP is a right triangle at BB with BAP=45\angle BAP = 45^\circ, AB=2AB = 2, BP=2BP = 2, and hypotenuse AP=22AP = 2\sqrt{2}
Since APBCAP \parallel BC, alternate interior angle relationships yield BAP=45\angle BAP = 45^\circ.
5
Calculate the area of quadrilateral ABCPABCP
Area(ABCP)=BC+AP2×h=2+222×2=(1+2)2=2+2\text{Area}(ABCP) = \frac{BC + AP}{2} \times h = \frac{2 + 2\sqrt{2}}{2} \times \sqrt{2} = (1 + \sqrt{2})\sqrt{2} = 2 + \sqrt{2}
Quadrilateral ABCPABCP is a trapezoid with parallel bases BC=2BC = 2 and AP=22AP = 2\sqrt{2} and height 2\sqrt{2}.

Anahtar Kavram

Properties of regular polygons, isosceles trapezoids, diagonal angles, and area decomposition.
Tahmini Süre:2m 30s
Soru 12Soru

In right trapezoid ABCDABCD, side ABAB is parallel to side DCDC, and DAB=90\angle DAB = 90^\circ. The lengths of the sides are AD=12AD = 12, AB=9AB = 9, and BC=13BC = 13, with DC>ABDC > AB. Point EE lies on the line containing segment DCDC such that segment BEBE is perpendicular to segment BCBC. What is the length of segment CECE?

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Cevap: 33.833.8

Cevap

The length of segment CECE is 33.833.8.
Dropping altitude BPBP from BB to side DCDC creates a rectangle ABPDABPD with height BP=12BP = 12 and a right triangle BPC\triangle BPC with legs BP=12BP = 12 and hypotenuse BC=13BC = 13. Applying the Pythagorean theorem yields PC=5PC = 5. Since segment BEBE is perpendicular to BCBC, triangle BCE\triangle BCE is a right triangle with right angle at BB and altitude BPBP to hypotenuse CECE. Using the leg rule BC2=PC×CEBC^2 = PC \times CE, we find 132=5×CE13^2 = 5 \times CE, which simplifies to CE=169/5=33.8CE = 169/5 = 33.8.

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1
Find the length of segment PCPC by dropping a perpendicular from BB to DCDC.
PC=5PC = 5
Let PP be the foot of the perpendicular from BB to line DCDC. Since ABCDABCD is a right trapezoid with ADDCAD \perp DC, ABPDABPD forms a rectangle. Thus BP=AD=12BP = AD = 12 and DP=AB=9DP = AB = 9. In right triangle BPC\triangle BPC, BP2+PC2=BC2    122+PC2=132    PC=169144=5BP^2 + PC^2 = BC^2 \implies 12^2 + PC^2 = 13^2 \implies PC = \sqrt{169 - 144} = 5.
2
Set up a similar triangle relationship for right triangle BCE\triangle BCE.
BPCEBC\triangle BPC \sim \triangle EBC
In BCE\triangle BCE, CBE=90\angle CBE = 90^\circ and BPCEBP \perp CE. Thus, right triangle BPC\triangle BPC is similar to right triangle EBC\triangle EBC because they share C\angle C.
3
Solve for the length of CECE.
CE=33.8CE = 33.8
By the geometric mean theorem (or ratio of corresponding sides in similar triangles), BCCE=PCBC    BC2=PC×CE\frac{BC}{CE} = \frac{PC}{BC} \implies BC^2 = PC \times CE. Substituting BC=13BC = 13 and PC=5PC = 5 yields 132=5×CE    169=5×CE    CE=1695=33.813^2 = 5 \times CE \implies 169 = 5 \times CE \implies CE = \frac{169}{5} = 33.8.

Anahtar Kavram

Pythagorean Theorem and Geometric Mean Theorem (Similar Right Triangles)
Tahmini Süre:1m 40s
Soru 13Soru

In circle OO, a sector with a central angle of 6060^\circ has an area of 6π6\pi. In circle PP, a sector with a central angle of 120120^\circ has an arc length equal to the arc length of the sector in circle OO. What is the area of the sector in circle PP?

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Cevap: 3π3\pi

Cevap

3π3\pi
The sector area of 3π3\pi is correctly calculated by first determining the radius of circle OO (r1=6r_1 = 6), using it to find the arc length (2π2\pi), setting that as the arc length for the sector in circle PP to find its radius (r2=3r_2 = 3), and finally computing its sector area 120360π(32)=3π\frac{120^\circ}{360^\circ} \cdot \pi (3^2) = 3\pi.

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1
Find the radius of circle OO
Radius r1=6r_1 = 6
The sector area formula is A=θ360πr2A = \frac{\theta}{360^\circ} \cdot \pi r^2. Given A=6πA = 6\pi and θ=60\theta = 60^\circ, we have 60360πr12=6π16r12=6r12=36r1=6\frac{60^\circ}{360^\circ} \cdot \pi r_1^2 = 6\pi \Rightarrow \frac{1}{6} r_1^2 = 6 \Rightarrow r_1^2 = 36 \Rightarrow r_1 = 6.
2
Calculate the arc length of the sector in circle OO
Arc length L=2πL = 2\pi
The arc length formula is L=θ3602πrL = \frac{\theta}{360^\circ} \cdot 2\pi r. Substituting θ=60\theta = 60^\circ and r1=6r_1 = 6, we get L=162π(6)=2πL = \frac{1}{6} \cdot 2\pi (6) = 2\pi.
3
Find the radius of circle PP
Radius r2=3r_2 = 3
The sector in circle PP has an arc length equal to 2π2\pi and a central angle of 120120^\circ. Using L=1203602πr2L = \frac{120^\circ}{360^\circ} \cdot 2\pi r_2, we get 2π=132πr2r2=32\pi = \frac{1}{3} \cdot 2\pi r_2 \Rightarrow r_2 = 3.
4
Calculate the area of the sector in circle PP
Sector area =3π= 3\pi
Using the sector area formula for circle PP: A2=120360πr22=13π(32)=3πA_2 = \frac{120^\circ}{360^\circ} \cdot \pi r_2^2 = \frac{1}{3} \cdot \pi (3^2) = 3\pi.

Anahtar Kavram

Relationship between central angles, radii, arc lengths, and sector areas in circles
Soru 14Soru

In the figure, line l1l_1 is parallel to line l2l_2. Point AA lies on line l1l_1, while points BB and CC lie on line l2l_2 such that BB is to the left of CC. Line segments ABAB and ACAC extend from line l1l_1 to line l2l_2 to form ABC\triangle ABC. The measure of interior angle BAC\angle BAC is (2x+10)(2x + 10)^\circ, the measure of interior angle ABC\angle ABC is (3x15)(3x - 15)^\circ, and the measure of the exterior angle at vertex CC along line l2l_2 is (6x35)(6x - 35)^\circ. What is the degree measure of angle BAC\angle BAC?

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Cevap: 7070^\circ

Cevap

The degree measure of angle BAC\angle BAC is 7070^\circ.
According to the Exterior Angle Theorem, the measure of an exterior angle of a triangle is equal to the sum of the measures of its two non-adjacent (remote) interior angles. Setting up the equation (2x+10)+(3x15)=6x35(2x + 10) + (3x - 15) = 6x - 35 gives 5x5=6x355x - 5 = 6x - 35, which simplifies to x=30x = 30. Substituting x=30x = 30 into the expression for BAC\angle BAC, (2x+10)(2x + 10)^\circ, yields 2(30)+10=702(30) + 10 = 70^\circ.

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1
Apply the Exterior Angle Theorem to set up an algebraic equation.
(2x+10)+(3x15)=6x35(2x + 10) + (3x - 15) = 6x - 35
The measure of an exterior angle of a triangle equals the sum of the measures of its two remote interior angles.
2
Simplify and solve the linear equation for xx.
5x5=6x35    x=305x - 5 = 6x - 35 \implies x = 30
Combining like terms yields 5x5=6x355x - 5 = 6x - 35. Subtracting 5x5x from both sides gives 5=x35-5 = x - 35, so x=30x = 30.
3
Substitute x=30x = 30 into the expression for angle BAC\angle BAC.
mBAC=2(30)+10=70\text{m}\angle BAC = 2(30) + 10 = 70^\circ
The question asks for the degree measure of angle BAC\angle BAC, which is given by (2x+10)(2x + 10)^\circ.

Anahtar Kavram

Exterior Angle Theorem and Angle Relationships in Parallel Lines
Soru 15Soru

In a circle centered at point OO, sector AOBAOB has a radius of length rr, a central angle of θ\theta degrees, an arc length of LL, an area of AsA_s, and a perimeter of PP. If the ratio of the sector area to the arc length is AsL=4\frac{A_s}{L} = 4, and the ratio of the sector area to the sector perimeter is AsP=43\frac{A_s}{P} = \frac{4}{3}, which of the following statements must be true? Select all that apply.

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Cevap: The radius rr of the circle is 88.; The area AsA_s of sector AOBAOB is 3232.; The perimeter PP of sector AOBAOB is 2424.

Cevap

The true statements are that the radius of the circle is 8, the area of the sector is 32, and the perimeter of the sector is 24.
The ratio of sector area to arc length simplifies directly to half the radius, r2=4\frac{r}{2} = 4, giving a radius of 88. Expressing the sector perimeter as the sum of the arc length and two radii (L+16L + 16) and using AsP=4LL+16=43\frac{A_s}{P} = \frac{4L}{L + 16} = \frac{4}{3} yields L=8L = 8. From this, the sector area is As=32A_s = 32 and the sector perimeter is P=24P = 24.

Adım Adım Çözüm

1
Relate sector area AsA_s and arc length LL to find the radius rr.
As=θ360πr2A_s = \frac{\theta}{360}\pi r^2 and L=θ3602πrL = \frac{\theta}{360}2\pi r, so AsL=r2=4    r=8\frac{A_s}{L} = \frac{r}{2} = 4 \implies r = 8.
Dividing the sector area formula by the arc length formula cancels the central angle fraction and π\pi.
2
Set up the ratio equation for AsP\frac{A_s}{P} using P=L+2rP = L + 2r.
Since r=8r = 8, P=L+16P = L + 16. Given As=4LA_s = 4L, we have 4LL+16=43    3L=L+16    2L=16    L=8\frac{4L}{L + 16} = \frac{4}{3} \implies 3L = L + 16 \implies 2L = 16 \implies L = 8.
Expressing both sector area and perimeter in terms of arc length allows direct solution for LL.
3
Calculate sector area AsA_s and perimeter PP.
As=4(8)=32A_s = 4(8) = 32 and P=8+2(8)=24P = 8 + 2(8) = 24.
Substituting L=8L = 8 and r=8r = 8 gives the exact values for area and perimeter.
4
Determine the central angle θ\theta.
8=θ3602π(8)    8=16πθ360    θ=(90π)28.658 = \frac{\theta}{360} \cdot 2\pi(8) \implies 8 = \frac{16\pi \theta}{360} \implies \theta = \left(\frac{90}{\pi}\right)^\circ \approx 28.65^\circ.
Plugging L=8L = 8 and r=8r = 8 into the arc length formula gives θ28.65\theta \approx 28.65^\circ, which is less than 6060^\circ.

Anahtar Kavram

Relating sector area, arc length, and perimeter using proportional ratios and fundamental circle formulas.
Soru 16Soru

A solid right circular cylinder has a base radius of rr and a height of 4r4r. A solid sphere has a radius of RR. If the total surface area of the sphere is equal to the total surface area of the cylinder, what is the ratio of the volume of the sphere to the volume of the cylinder?

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Cevap: 51012\frac{5\sqrt{10}}{12}

Cevap

The ratio of the volume of the sphere to the volume of the cylinder is 51012\frac{5\sqrt{10}}{12}.
The total surface area of the cylinder is the sum of its lateral area and two circular bases: 2πr(4r)+2πr2=10πr22\pi r(4r) + 2\pi r^2 = 10\pi r^2. Setting this equal to the sphere's surface area 4πR24\pi R^2 yields R/r=5/2=10/2R/r = \sqrt{5/2} = \sqrt{10}/2. The ratio of the sphere's volume 43πR3\frac{4}{3}\pi R^3 to the cylinder's volume πr2(4r)=4πr3\pi r^2 (4r) = 4\pi r^3 is 13(R/r)3=13(102)3=51012\frac{1}{3}(R/r)^3 = \frac{1}{3} \left(\frac{\sqrt{10}}{2}\right)^3 = \frac{5\sqrt{10}}{12}.

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1
Calculate the total surface area of the cylinder.
TSAcyl=2πr2+2πrh=2πr2+2πr(4r)=10πr2\text{TSA}_{\text{cyl}} = 2\pi r^2 + 2\pi r h = 2\pi r^2 + 2\pi r(4r) = 10\pi r^2
A cylinder's total surface area consists of two circular bases (2×πr22\times\pi r^2) and the lateral surface area (2πrh2\pi r h).
2
Equate the total surface area of the sphere to the total surface area of the cylinder to find the ratio of RR to rr.
4πR2=10πr2    R2=52r2    Rr=52=1024\pi R^2 = 10\pi r^2 \implies R^2 = \frac{5}{2}r^2 \implies \frac{R}{r} = \sqrt{\frac{5}{2}} = \frac{\sqrt{10}}{2}
The total surface area of a sphere of radius RR is 4πR24\pi R^2.
3
Express the volumes of both figures in terms of rr and RR.
Vsph=43πR3V_{\text{sph}} = \frac{4}{3}\pi R^3 and Vcyl=πr2h=πr2(4r)=4πr3V_{\text{cyl}} = \pi r^2 h = \pi r^2 (4r) = 4\pi r^3
The volume of a sphere is 43πR3\frac{4}{3}\pi R^3 and the volume of a cylinder is πr2h\pi r^2 h.
4
Compute the ratio of the volume of the sphere to the volume of the cylinder.
VsphVcyl=43πR34πr3=13(Rr)3=13(102)3=1310108=51012\frac{V_{\text{sph}}}{V_{\text{cyl}}} = \frac{\frac{4}{3}\pi R^3}{4\pi r^3} = \frac{1}{3}\left(\frac{R}{r}\right)^3 = \frac{1}{3}\left(\frac{\sqrt{10}}{2}\right)^3 = \frac{1}{3} \cdot \frac{10\sqrt{10}}{8} = \frac{5\sqrt{10}}{12}
Substitute Rr=102\frac{R}{r} = \frac{\sqrt{10}}{2} into the ratio expression.

Anahtar Kavram

Relating 3D surface area formulas to volume formulas for cylinders and spheres
Tahmini Süre:2m 0s
Soru 17Soru

Two straight lines, L1L_1 and L2L_2, intersect at point OO. One of the angles formed by their intersection measures (3x15)(3x - 15)^\circ, and the vertically opposite angle measures (x+25)(x + 25)^\circ. What is the degree measure of an angle adjacent to (3x15)(3x - 15)^\circ?

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Cevap: 135135^\circ

Cevap

135135^\circ
Since vertically opposite angles are equal, setting 3x15=x+253x - 15 = x + 25 yields x=20x = 20. Substituting x=20x = 20 into 3x153x - 15 gives an angle of 4545^\circ. Because adjacent angles on intersecting lines form a straight line (a linear pair), they are supplementary. Therefore, the adjacent angle measures 18045=135180^\circ - 45^\circ = 135^\circ.

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1
Set the vertically opposite angle expressions equal to each other.
3x15=x+253x - 15 = x + 25
Vertically opposite angles formed by two intersecting lines are equal in measure.
2
Solve for the variable xx.
2x=40    x=202x = 40 \implies x = 20
Subtract xx and add 1515 to both sides of the equation.
3
Calculate the degree measure of the angle (3x15)(3x - 15)^\circ.
3(20)15=6015=453(20) - 15 = 60 - 15 = 45^\circ
Substitute x=20x = 20 back into the angle expression.
4
Calculate the measure of an adjacent angle.
18045=135180^\circ - 45^\circ = 135^\circ
Adjacent angles along a straight line are supplementary and sum to 180180^\circ.

Anahtar Kavram

Vertically opposite angles are equal, and adjacent angles forming a linear pair are supplementary.
Soru 18Soru

A sector of a circle with a radius of 1212 units has an area of 24π24\pi square units. What is the measure, in degrees, of the central angle of the sector?

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Cevap: 60

Cevap

The measure of the central angle of the sector is 6060^\circ.
The area of the full circle is πr2=π(12)2=144π\pi r^2 = \pi (12)^2 = 144\pi. The sector area represents a fraction of the total area, specifically 24π144π=16\frac{24\pi}{144\pi} = \frac{1}{6}. Multiplying this fraction by the full circle's central angle of 360360^\circ gives 16×360=60\frac{1}{6} \times 360^\circ = 60^\circ.

Adım Adım Çözüm

1
Find the total area of the circle
The total area of the circle is π×122=144π\pi \times 12^2 = 144\pi.
The area of a full circle with radius rr is given by A=πr2A = \pi r^2.
2
Relate the sector area to the total circle area
The fraction of the circle represented by the sector is 24π144π=16\frac{24\pi}{144\pi} = \frac{1}{6}.
The area of a sector is proportional to the fraction of the total central angle (360360^\circ) it subtends.
3
Calculate the central angle in degrees
\theta = \frac{1}{6} \times 360^\circ = 60^\circ.
Multiply the fraction of the circle by 360360^\circ to get the central angle measure.

Anahtar Kavram

Relationship between central angle measure, total circle area, and sector area
Soru 19Soru

A triangle has a base of length 1414 centimeters and an area of 4242 square centimeters. What is the height, in centimeters, of the triangle perpendicular to this base?

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Cevap: 6

Cevap

The height of the triangle perpendicular to the base is 6 centimeters.
The area of a triangle is given by Area=12×base×height\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}. Substituting 4242 for the area and 1414 for the base yields 42=12×14×h42 = \frac{1}{2} \times 14 \times h, which simplifies to 42=7h42 = 7h. Dividing 4242 by 77 gives h=6h = 6.

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1
Write down the triangle area formula.
Area=12×base×height\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}
The area and base are known values, and the goal is to solve for the perpendicular height.
2
Substitute the given values into the formula.
42=12×14×height42 = \frac{1}{2} \times 14 \times \text{height}
Plugging in Area=42\text{Area} = 42 and base=14\text{base} = 14 creates a single-variable algebraic equation.
3
Solve for the height.
42=7×height    height=642 = 7 \times \text{height} \implies \text{height} = 6
Simplifying 12×14\frac{1}{2} \times 14 to 77 and dividing both sides by 77 yields the height.

Anahtar Kavram

The area of a triangle is calculated using the formula Area = (1/2) * base * height.
Soru 20Soru

Lines l1l_1 and l2l_2 intersect at point PP to form an acute angle measuring 4444^\circ. Line b1b_1 is the angle bisector of this acute angle. A third line, l3l_3, is drawn perpendicular to b1b_1 and intersects line l1l_1 at point QQ (where QPQ \neq P). What is the measure, in degrees, of the acute angle formed by the intersection of line l2l_2 and line l3l_3?

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Cevap: 6868^\circ

Cevap

The measure of the acute angle formed by the intersection of line l2l_2 and line l3l_3 is 6868^\circ.
The correct answer is 6868^\circ. Line b1b_1 divides the 4444^\circ angle between l1l_1 and l2l_2 into two 2222^\circ angles. Because line l3l_3 is perpendicular to b1b_1, it forms a right triangle with l1l_1 and b1b_1, making the angle between l1l_1 and l3l_3 equal to 9022=6890^\circ - 22^\circ = 68^\circ. Considering the large triangle formed by lines l1l_1, l2l_2, and l3l_3, two of its angles are 4444^\circ and 6868^\circ. Thus, the third interior angle at the intersection of l2l_2 and l3l_3 is 180(44+68)=68180^\circ - (44^\circ + 68^\circ) = 68^\circ, which is acute.

Adım Adım Çözüm

1
Determine the angle formed by the angle bisector b1b_1 with line l1l_1 and line l2l_2.
Since line b1b_1 bisects the 4444^\circ acute angle between l1l_1 and l2l_2, the angle between l1l_1 and b1b_1 is 442=22\frac{44^\circ}{2} = 22^\circ, and the angle between l2l_2 and b1b_1 is also 2222^\circ.
An angle bisector divides an angle into two equal congruent parts.
2
Find the measure of the interior angle between line l1l_1 and line l3l_3.
Line l3l_3 is perpendicular to b1b_1, forming a right triangle with l1l_1 and b1b_1. The interior angle between l1l_1 and l3l_3 is 1809022=68180^\circ - 90^\circ - 22^\circ = 68^\circ.
The sum of interior angles in any triangle is 180180^\circ.
3
Calculate the interior angle at the intersection of line l2l_2 and line l3l_3 in the main triangle formed by l1l_1, l2l_2, and l3l_3.
The interior angle at the intersection of l2l_2 and l3l_3 is 1804468=68180^\circ - 44^\circ - 68^\circ = 68^\circ.
The interior angles of the triangle formed by lines l1l_1, l2l_2, and l3l_3 must sum to 180180^\circ.
4
Verify that the calculated angle is acute.
Since 68<9068^\circ < 90^\circ, the acute angle formed by lines l2l_2 and l3l_3 is 6868^\circ.
An angle measuring strictly less than 9090^\circ is defined as an acute angle.

Anahtar Kavram

Angle bisector properties, perpendicular lines, and interior angle sum theorem for triangles.
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