Question

(sin4x + sin4y) tan(2x-2y) /(sin4x -sin4y)

Answer 1

Answer:

tan2(x+y)

2sin2(x+y)cos2(x-y)sin2(x-y)/cos2(x-y)2sin2(x-y)cos2(x-y)

all got cancel out except sin2(x+y)/cos2(x+y)=tan2(x+y)