Trig Identity Help Plz

I've been trying to do this problem but I am stuck and since your all so nice :) can someone help me prove this?

If A,B, and C are the angles of any triagle show that

sin A+ sin B + sin C= 4cosA/2 cos B/2 cos C/2


Thank you for your help.

This is what I have so far..
- (a) sin C = sin(A + B).
- (B) sin A + sin B + sin (A + B) = 2 sin ((A+B)/2) ( cos ((A-B)/2) + cos ((A+B)/2) ).

e=mc2

Graph it and you'll get the answer.