Question

prove sin^4 (theta) -cos^4 (theta) = 1-2sin^2 (theta)

Answer 1

Step-by-step explanation:

sin⁴θ-cos⁴θ=(sin²θ)²-(cos²θ)²

=(sin²θ+cos²θ)(sin²θ-cos²θ)

=1(sin²θ-1+sin²θ)

=2sin²θ-1