show that sin4x + 2sin2x = 8sinxcos^3x
The Attempt at a Solution
I started out by letting sin4x = sin(2x*2) so that I could plugg in sin2x = 2sinxcosx in the equation.
sin(2x*2) +2sin2x =
sin2*sin2x +2sin2x =
sin2 * (2sinxcosx) + 2*sin2x =
sin2* (2sinxcosx) + 2* (2sinxcosx)
and I end up with 8sinxcosx
which is wrong!