Answer:
The function of the graph is y = 3 cos (4x) ⇒ answer A
Step-by-step explanation:
- If the equation is y = A cos (B x)
* A is the amplitude
- The amplitude is the height from highest to lowest points and
divide the answer by 2
* The period is 2π/B
- The period is the distance from one peak to the next peak
* Lets look to the graph
- The maximum value is 3 and the minimum value is -3
∵ The height from the maximum point to the minimum point is
3 - (-3) = 3 + 3 = 6
∴ The amplitude is 6/2 = 3
∵ A is the amplitude
∴ A = 3
- The distance between two consecutive peaks is π/2
∵ The period is the distance from one peak to the next peak
∴ The period = π/2
∵ The period = 2π/B
∴ 2π/B = π/2 ⇒ divide both sides by π
∴ 2/B = 1/2 ⇒ by using cross multiplication
∴ B = 4
- Lets write the form of the function
∵ y = A cos (Bx)
∵ A = 3 and B = 4
∴ y = 3 cos (4x)
* The function of the graph is y = 3 cos (4x)
