Question

how do i verify the identity cos 2 theta= 2 cos^2-i using an angel sum idenrtity

Answer 1

Proof for: \(\cos2\theta=2\cos^2\theta-1\):
\(\cos 2\theta=\cos^2\theta-\sin^2\theta\) **
\(=\cos^2\theta-(1-\sin^2\theta)\)
\(=2\cos^2\theta-1\)

**Remember: \(cos(a+b)=\cos a \cos b-\sin a \sin b\)

Answer 2

epic thank you