Question

How can I simplify this expression using only cos and sin? cos2(2x)-sin(2x)

Answer 1

do you mean that??.
\[\cos ^{2}(2x)-\sin(2x)\]

Answer 2

yep!

Answer 3

\[\cos(2x)=2\cos ^{2}x-1\]
\[\sin(2x)=2sinx*cosx\]
can you continue??

Answer 4

well I would need to square the first term, but after that, I don't know what the next step wuld be...

Answer 5

4cos^4(x)-4cos^2(x)=1-2sinxcosx