$1-\sin^2\left(t\right)+\tan^2\left(t\right)-\tan^2\left(t\right)\sin^2\left(t\right)$

$tana^2-2tan^2b=1$

$\frac{x^4-2x^3+5}{x-2}$

$\frac{x}{\:x+2}-\frac{1}{x-2}=\frac{8}{x^2-4}$

$\cos\left(x\right)-\left(\cos\left(x\right)\cdot\sin^2\left(x\right)\right)=\cos\left(x\right)$

$16+18y-13+5y$

$4n^2-28n+49$