Question

cos4x = 1-8 sin^2x cos^2x

Answer 1

hope it helps u......friend.....

Answer 2

cos4x=cos2(2x)

cos4x=1-2sin²2x

cos4x=1-2(sin2x)²

cos4x=1-2(2sinxcosx)²

cos4x=1-2(4sin²xcos²x)

cos4x=1-8sin²xcos²x