Answer:
Step-by-step explanation:
sin(x+y) = sin(x)cos(y) + sin(y)cos(x)
sin(x-y) = sin(x)cos(y) - sin(y)cos(x)
Sin(x+y)sin(x-y) = (sin(x)cos(y) + sin(y)cos(x))(sin(x)cos(y) - sin(y)cos(x))
= sin^2(x)cos^2(y) - sin^2(y)cos^2(x)
= sin^2(x)(1-sin^2(y)) - sin^2(y)(1-sin^2(x))
= sin^2(x) - sin^2(x)sin^2(y) - sin^2(y) + sin^2(x)sin^2(y)
= sin^2(x) - sin^2(y)
So L.H.S=R.H.S
Hence proved
