Question

Difficulty: EasyGraphs of Trigonometric Functions

Match each of the trigonometric functions listed on the left with the correct description of its amplitude and period listed on the right.

  • y=3sin(2x)y = 3\sin(2x)Amplitude is 3 and period is π\pi
  • y=2cos(3x)y = 2\cos(3x)Amplitude is 2 and period is 2π3\frac{2\pi}{3}
  • y=4sin(πx)y = 4\sin(\pi x)Amplitude is 4 and period is 2

Answer

The function y=3sin(2x)y = 3\sin(2x) matches the description stating 'Amplitude is 3 and period is π\pi'. The function y=2cos(3x)y = 2\cos(3x) matches the description stating 'Amplitude is 2 and period is 2π3\frac{2\pi}{3}'. The function y=4sin(πx)y = 4\sin(\pi x) matches the description stating 'Amplitude is 4 and period is 2'.
Each trigonometric function of the form y=asin(bx)y = a\sin(bx) or y=acos(bx)y = a\cos(bx) has an amplitude equal to the absolute value of the coefficient of the trigonometric term (a|a|) and a period equal to 2π2\pi divided by the absolute value of the coefficient of the angle variable (b|b|). Applying these formulas gives the correct properties for each function.

Step-by-Step Solution

1
Identify the general form of the trigonometric functions
The functions are in the form y=asin(bx)y = a\sin(bx) or y=acos(bx)y = a\cos(bx), where the amplitude is given by the absolute value of the vertical stretch coefficient (a|a|), and the period is calculated as 2πb\frac{2\pi}{|b|}.
This establishes the formulas needed to determine the amplitude and period for each equation.
2
Calculate the properties for y=3sin(2x)y = 3\sin(2x)
The vertical stretch coefficient is 3, so the amplitude is 3. The frequency coefficient is 2, so the period is 2π2=π\frac{2\pi}{2} = \pi.
To find the amplitude and period for the first function.
3
Calculate the properties for y=2cos(3x)y = 2\cos(3x)
The vertical stretch coefficient is 2, so the amplitude is 2. The frequency coefficient is 3, so the period is 2π3\frac{2\pi}{3}.
To find the amplitude and period for the second function.
4
Calculate the properties for y=4sin(πx)y = 4\sin(\pi x)
The vertical stretch coefficient is 4, so the amplitude is 4. The frequency coefficient is π\pi, so the period is 2ππ=2\frac{2\pi}{\pi} = 2.
To find the amplitude and period for the third function.

Key Concept

Identifying the amplitude and calculating the period of trigonometric functions from their equations
Estimated Time:1m 30s
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