Question

20sin^4 x power reduction

Answer 1

Explanation:

20 sin^4x

=5(4sin^4 x)

=5(2sin²x)²

=5(1-cos 2x)²

=5(1-4cos2x+cos²(2x))

=5[1-4cos(2x)+{1+cos (4x)}/2]

=5/2[2-8cos(2x)+1+cos(4x)]

=5/2[3-8cos (2x)+cos (4x)]