Verified answer

This cannot be verified because it is not true.

cos²x - sin²x = 1 - 2 sin²x

I'm sure you mean cos²x - sin²x ≡ 1 - 2sin²x

Well, cos²x + sin²x = 1

so, cos²x = 1 - sin²x

=> cos²x - sin²x = 1 - sin²x - sin²x => 1 - 2sin²x...R.H.S.

:)>