If a + b + C = Pi show that Cos A + cos b + cos c=1 + 4 sin a/2 sin b/2 sin c/2

If a + b + C = Pi show that Cos A + cos b + cos c=1 + 4 sin a/2 sin b/

1.	If a + b + C = Pi show that Cos A + cos b + cos c=1 + 4 sin a/2 sin b/2 sin c/2
Answer» Same here. Dont know. don\'t know