Question

find sum into product form sin c + sin d​

Answer 1

Product formula

sin C + sin D = 2 sin[(C + D) / 2]cos[(C - D) / 2]

sin C - sin D = 2 cos[(C + D) / 2]sin[(C - D) / 2]

cos C + cos D = 2 cos [(C + D) / 2]cos[(C - D) / 2]

cos C - cos D = - 2 sin [(C + D) / 2]sin[(C - D) / 2]