The below integration makes use of the following trig identities:
1. The Pythagorean identity: $\sin^2(x) + \cos^2(x) = 1$
2. The derivative of sine: $\frac{d}{dx}sin(x) = cos(x)$
3. The derivative of cosine: $\dfrac{d}{dx} \cos(x) = -\sin(x)$
$$ \cos^2(x) = \frac{}