Question

Express into product: sin 20+ sin 40​

Answer 1

Step-by-step explanation:

sinC +sinD= 2sin{(C+D)/2}•cos{(C-D)/2}

sin20+ sin40= 2sin{(40+20)}•cos(20-40)}

sin20+ sin40= 2sin60•cos(-10)

sin20+ sin40= 2sin60•cos10

sin20+ sin40= 2×√3/2•cos10

sin20+ sin40= √3cos10

#666