Question

Difficulty: MediumGraphs of Trigonometric Functions

Match each trigonometric function on the left with its correct combination of amplitude and period on the right.

  • f(x)=4sin(3x)f(x) = 4 \sin(3x)Amplitude = 44, Period = 2π3\frac{2\pi}{3}
  • g(x)=2cos(12x)g(x) = 2 \cos\left(\frac{1}{2}x\right)Amplitude = 22, Period = 4π4\pi
  • h(x)=3sin(2x)h(x) = -3 \sin(2x)Amplitude = 33, Period = π\pi

Answer

f(x)=4sin(3x)f(x) = 4 \sin(3x) matches Amplitude = 4, Period = 2π3\frac{2\pi}{3}; g(x)=2cos(12x)g(x) = 2 \cos\left(\frac{1}{2}x\right) matches Amplitude = 2, Period = 4π4\pi; h(x)=3sin(2x)h(x) = -3 \sin(2x) matches Amplitude = 3, Period = π\pi.
Each trigonometric function is correctly evaluated using the general properties: Amplitude equals A|A| and Period equals 2πB\frac{2\pi}{|B|}.

Step-by-Step Solution

1
Identify the standard trigonometric form parameters.
For equations of the form y=Asin(Bx)y = A \sin(Bx) or y=Acos(Bx)y = A \cos(Bx), Amplitude =A= |A| and Period =2πB= \frac{2\pi}{|B|}.
Applying the definitions of amplitude and period for sine and cosine functions.
2
Calculate amplitude and period for f(x)=4sin(3x)f(x) = 4 \sin(3x).
Amplitude =4=4= |4| = 4, Period =2π3= \frac{2\pi}{3}.
Here A=4A = 4 and B=3B = 3.
3
Calculate amplitude and period for g(x)=2cos(12x)g(x) = 2 \cos\left(\frac{1}{2}x\right).
Amplitude =2=2= |2| = 2, Period =2π1/2=4π= \frac{2\pi}{1/2} = 4\pi.
Here A=2A = 2 and B=12B = \frac{1}{2}.
4
Calculate amplitude and period for h(x)=3sin(2x)h(x) = -3 \sin(2x).
Amplitude =3=3= |-3| = 3, Period =2π2=π= \frac{2\pi}{2} = \pi.
Here A=3A = -3 (so A=3|A| = 3) and B=2B = 2.

Key Concept

Amplitude and Period of Sine and Cosine Graphs
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