1. ## Factoring Identities

Factor the expression and use fundamental identities..

cos^2xsin^2x-cos^2x

2. Originally Posted by jumpman23
Factor the expression and use fundamental identities..

cos^2xsin^2x-cos^2x
Factor out a $\cos^2x$ and use the Pythagorean identity, $\sin^2x+\cos^2x=1.$

Hint:
Spoiler:
$\sin^2x-1=-\left(1-\sin^2x\right)=-\cos^2x$

Or you could just factor out $-\cos^2x$ right from the start.