Solution :
The formula of sin (A + B + C) is sin A cos B cos C + cos A sin B cos C + cos A cos B sin C – sin A sin B sin C.
Proof :
We have,
sin (A + B + C) = sin ((A + B) + C) = sin (A + B) cos C + cos (A + B) sin C
sin (A + B + C) = (sin A cos B + cos A sin B) cos C + (cos A cos B – sin A sin B) sin C
sin (A + B + C) = sin A cos B cos C + cos A sin B cos C + cos A cos B sin C – sin A sin B sin C