# Math Help - Equation

1. ## Equation

How to prove?
$cos 2x + cos x = sin^2 x$
All Ive got so far is $cos^2 x - sin^2 x + cos x = sin^2 x$

2. Let's see, cos(2 * 0) + cos(0) = 2. Hmm...

3. It should read "solve", and we've already addressed this (7 minutes ago) at mymathforum!

I'm ok with you replying in either place... Obviously

4. Now substitute $\displaystyle \sin^2{x} = 1 - \cos^2{x}$ to get a quadratic equation in $\displaystyle \cos{x}$, which you will be able to solve.

5. Yeah, I said that already!