If you correctly use parentheses to show the identity, then it is true:
I will assume that you are submitting all of the large number of similar problems I see here waiting to be answered.
You won't learn anything by having us do all of these for you. You need to do them yourself.
I will do this one more for you. But you should be somewhat ashamed to have asked it, since this one is trivial.
The general method for all the proofs is the same:
(1) Get everything in terms of sine and cosine -- most of the identities you use will involve sines and cosines. Sometimes (as in this case) just this one step will complete the proof.
(2) If more is needed, look for a commonly used identity to change the form of the expression you are working on. Probably 90% of the time, the identity you will use is sinx^2+cosx^2 = 1.
And don't forget that you should only work on one side to make it look like the other side....
Okay, so here is this one....
Work on the right hand side to make it look like the left hand side:
