Use power reducing formula to rewrite in first power of cosine

Question

Cos²x tan²x

Answer 1

Well tan^2(x) is sin^2(x)/cos^2(x), so your expression would just yield sin^2(x). But your teacher wants you to rewrite this in the first power of cosine. According to the power reducing formulas (which you can google), sin^2(x) = 0.5 - 0.5*cos(2x)