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

$-24\:-\:34\:+\:76\:-\:28$

$\frac{x^3+2ax^2+bx+5}{x^2+3x+2}$

$\left(9x^2+5y\right)^2$

$4\left(1+5y\right)$

$-2x-12x+5$

$\frac{d^4}{dx^4}\left(x\cdot\cos\left(2x\right)\right)$