Question

Rewrite with only sin x and cos x.

cos 3x

Answer 1

cos(3x) --> cos³(x) - 3sin²(x)cos(x)

Explanation:

The text in pink are the trig identities I used to convert cos(2x) and sin(2x) into their other equivalent forms.

This question is pretty much asking if you know how to use your trig identities if i understand it correctly.