Question

Use basic identities to simplify the expression.

cos θ - cos θ sin^2θ
please help >.<

Answer 1

first, factor out!
cos θ - cos θ sin^2 θ
= cos θ(1 - sin^2 θ)
use the identity " (1 - sin^2θ) = cos^2 θ
= cosθ cos^2 θ
= cos^3 θ