I'm having trouble with the following-

Show: $$\frac{\cos 3x + i\sin 3x}{\cos x + i\sin x} = \cos 2x + i\sin 2x$$

I have tried both multiplying by the complex conjugate of the denominator and alternatively trigonometric identities, but the results don't get close

Can anybody give me any pointers in the right general direction? 

Thanks for the help