- #1

- 50

- 0

## Homework Statement

show that sin4x + 2sin2x = 8sinxcos^3x

## Homework Equations

sin2x =2sinxcosx

## 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!

??