Converting Between Products and Sums

Question

sin4θ - sin2θ = _____

2cos3θcosθ

2cos3θsinθ

2sin3θcosθ

2sin3θsinθ

Answer 1

sin x - sin y = 2 cos [(1/2)(x+y)] sin [(1/2)(x-y)] ... and I had to look it up in a textgbook!

When you plug in the values given you get 2 cos 3θ sin θ