Equation

• March 11th 2011, 10:19 AM
Critter314
Equation
How to prove?
$cos 2x + cos x = sin^2 x$
All Ive got so far is $cos^2 x - sin^2 x + cos x = sin^2 x$
• March 11th 2011, 10:23 AM
emakarov
Let's see, cos(2 * 0) + cos(0) = 2. Hmm...
• March 11th 2011, 10:36 AM
TheChaz
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.