Question

simplifique cos ²x. tg²x - cotg ²x. sen² x

Answer 1

$cos^2(x).tg^2(x)-cotg^2(x).sen^2(x)=\\ \\ cos^2(x).\frac{sen^2(x)}{cos^2(x)}-\frac{cos^2(x)}{sen^2(x)}.sen^2(x)=\\ \\ \boxed{sen^2(x)-cos^2(x)}=-cos(2x)$