Why not just expand out the LHS, and use a familiar identity to simplify? What do you get?
I need help with the following question:
Prove the identity.
(sinx + cosx) ^2 = 1 + 2sinx cosx
I know that I have to split the equation into two sides, left hand side and right hand side, and then reduce the most difficult side. However, I'm not sure which side is the most difficult side or how to start reducing.
I know that using the double angle formula sin2x = 2sinx cosx, that I can make the right side 1 + sin2x but I'm not sure if that helps at all.