Question

Find an equation for a sinusoidal function that has period 360°, amplitude 1, and contains the point (–270°,0).

Write your answer in the form f(x)=Acos(Bx+C)+D, where A, B, C, and D are real numbers.

Answer 1

y = f(x + 90)

Explanation:

f(x)=Acos(Bx+C)+D,

A is the amplitude: A = 1

B is the 360/period: 360/360 = 1

D is the mean line: y = 0

f(-270) = 0

sin(x + C) = 0

-270 + C = -180

C = 90

y = f(x + 90)