$\frac{\sin\left(a\right)}{1-\cos\left(a\right)}\cdot\frac{\cos\left(a\right)}{\sin\left(a\right)}$

$\frac{-16^2}{n}$

$\int_1^a\left(\frac{1}{x^p}\right)dx$

$t^2-6t-9$

$4csc^2\left(x\right)-2=0$

$-7\left(6r\right)$

$series\frac{2^{6n}}{6^{2n}}\left(\frac{x}{3}\right)^n$