Question

Prove: sin θ - sin θ•cos2 θ = sin3 θ. You must show all work.

Answer 1

sin²α+сos²α=1            sin²α=1-cos²α

sin θ - sin θ•сos²θ =  sin³ θ

sin θ - sin θ•сos²θ
=sin θ(1-сos²θ)
=sin θ·sin²θ
=sin³ θ