Ask Me Help Desk - Verify this identity: cos^2x=(1/2)cos2x

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Verify this identity: cos^2x=(1/2)cos2x

A friend asked me to try to help, and I can't get it.

I think the identity you are trying to solve for is:

$\cos^2(x) = \frac{1}{2} + \frac{1}{2} \cos(2x)$

Remember the identities:
$\cos^2(x) + \sin^2(x) = 1$
and
$\cos (2x) = \cos^2(x) - \sin^2(x)$

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