Question

sin^2acos^2b - cos^2a sin^b

Answer 1

sin^2a cos^2b - cos^2a sin^2b

= sin^2a (1 - sin^2 b) - (1 - sin^2a) sin^2b [Since cos^2x = 1 - sin^2x]

= sin^2a - sin^2a sin^2b -sin^2b + sin^2a sin^2b

= sin^2a - sin^2b

Answer 2

sin2a.cos2b - sin2b.cos2a

sin2a.cos2 (90-b) - sin2b. cos2 (90-a)

sin2a.sin2b - sin2b.sin2a = 0