please help!
(sqrt3)cosx + sin2x = 0
I assume you want to find x which makes the equation true.
Recall your double-angle identity for sine
√3 cosx + sin2x = 0
√3 cosx + 2 sinx cosx = 0
cosx (√3 + 2sinx) = 0
Now you should be able to solve for each of those factors.
Be watchful for trick questions ...