Alright so I've got the question:
And in class I learned:
$\sin^2(x) = ((1-\cos(2x))/2)$
$\cos^2(x) = ((1+\cos(2x))/2)$
So when I substitute I get:
But according to the almighty wolfram, those two aren't the same integral. What did I do wrong? And furthermore, how to I proceed?