# Math Help - equivalent sin and cos functions

1. ## equivalent sin and cos functions

determine an equivalent sine function for the cosine function.
y=-cos2(x-pi/12)

determine an equivalent cosine function for each sine function
y=2sin4(x+pi)

thank you

2. Originally Posted by johett
determine an equivalent sine function for the cosine function.
y=-cos2(x-pi/12)
use the fact that $\sin^2 \theta = \frac {1 - \cos 2 \theta}2$

determine an equivalent cosine function for each sine function
y=2sin4(x+pi)
use the fact that $\sin \theta = \sqrt {1 - \cos^2 \theta}$