In any triangle sin(A + B)= sinC

State true or false and explain why.

The angles A,Band C are alpha, betta and gamma I just dont know how to put that in there so I used A,B andC.

I tried to use an addition formula for sin and expand A+B to sines and cosines but I dont think that is right. The teacher wrote on the paper A+B=180-C which makes sense but there must be more than just that. If someone could get me going in the right direction I would appreciate it.