Question

Prove sin^2 theta-sin^2 theta is sin tetha sin 3 thetahow to prove..pls help!! thanksss

Answer 1

Simply you can substitute theta=45 degrees (or any angle,not zero) in left hand side and right hand side.

or 

using a^2 - b^2 =(a+b)(a-b)

= sin(2x+x)sin(2x-x)
= sin 3x sin x