Question

cos^2x-sin^2x=1-2sin^2x
need help showing step by step to prove identity

Answer 1

well you know

cos^2 + sin^2 = 1

make cos^2 the substitute and then substitute into the equation...

Answer 2

\(\bf cos^2(\theta)+sin^2(\theta)=1\implies cos^2(\theta)={\color{blue}{ 1-sin^2(\theta)}}\\ \quad \\ \quad \\
cos^2(x)-sin^2(x)\implies {\color{blue}{ 1-sin^2(x)}}-sin^2(x)\)