NEED ASAP! Verify following identity:

Question

sin⁴(θ) - cos⁴(θ) = sin² (θ) - cos²(θ)

Answer 1

call cosx x, and sinx y

y⁴-x⁴=y²-x²

same as

(y²+x²)(y²-x²)=y²-x²

in this scheme, (y²+x²)=sin²x+cos²x

and sin²x+cos²x=1

left with (y²-x²)=y²-x²

Answer 2

cos⁴ θ = (1 - sin² θ)²

Start with that.