i got left side equals right side..which is 1-4sin^2x
1) Please add parentheses to clarify meaning.
Is it as you have written it or did you mean (sin(4x)-sin(2x))/sin(2x)?
2) Please show your work. It's nice that you managed some result, but how did you do that?
3) When you get left side = right side, you are done.
Where does that leave us?