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

$sin^2\left(wt\right)-icos\left(wt\right)sin\left(wt\right)$

$3\cdot\left[4x-1\right]>10x$

$\lim_{n\to\infty}\left(cos\left(n\cdot\pi\right)\right)$

$\lim_{x\to0}\left(\frac{2+x^2+\cos\left(x\right)}{x^{12}}\right)$

$36x^2+45x+9$

$\frac{16x-25}{4x^2+19x-5}$