I was doing an advance reading on trigonometry (identities, specifically) when I encountered these problems on verification:

sin 5x = 5 sin x - 20 sin^3 x + 16 sin ^ 5 y

sin 2x + sin 2y + sin 2z = 4 sin x sin y sin z

sin^2 x + sin ^2 (y-x) + 2 sin x cos y sin (y-x) = sin^2 y

I'll try to edit this when I come up with answers. Just tips or hints on what identities I should use will do. Thanks for those who will help!