Question

sin5x + sin3x / cos6x sin10x - cos10x sin6x

Answer 1

cos10x sin6x-sin3x :21-sin5x

Answer 2

(sin5x + sin3x) /( cos6x sin10x - cos10x sin6x)=
={2sin(5x+3x)/2 cos(5x-3x)/2} /  sin(10x-6x)=
=(2 sin4x cos x) /  sin4x) =2 cosx