Can this: $\frac{\cos x}{4 + \sin^2 x}$
Be re-written using the fact that: $\cot(t) = \frac{\cos (t)}{\sin (t)} = \frac{1}{\tan (t)}$
I'm not good with algebra, but I'm getting there. I'm trying to simplify this expression, it's an integration by substitution task. I just don't see how I can separate $\cos x$ and $\sin x$ from the original equation.