circular functions

Question

Determine the phase shift of the function 𝑦 = 2cos ( 3𝑥 − 12 )

Answer 1

The definition for cosine is:

Acos(B(x-C))+D

A= amplitude = 2

B = 2π/period = 3

C = phase shift right (since negative)

D = vertical shift = 0

So BC = 12 = 3C ==> C = 12/3 = 4 units right