CPM Homework Help : APCALC Problem 7-155

Use the identity $\cos(2x) = 2 \cos^2(x) - 1$ to evaluate $\int 4 \operatorname { cos } ^ { 2 } ( x ) d x$ .

Hint:

$\int 4\cos^{2}(x)dx=2\int 2\cos^{2}(x)-1+1dx=$