$$\frac { 1 } { 1 - \cos \theta } + \frac { 1 } { 1 + \cos \theta }$$
$\frac{2}{\left(\sin(\theta )\right)^{2}}$
$-\frac{2\sin(2\theta )}{\left(-\left(\cos(\theta )\right)^{2}+1\right)^{2}}$
