$cot\left(20\right)-\frac{\cos\left(20\right)}{\sin\left(70\right)}$

$1-9x^2$

$-x^3+11x^2-36x+36$

$\sin^2x+9=10-\cos^2x$

$200\cdot9$

$\frac{\cos\:\left(2x\right)}{\sin\left(2x\right)+1}=\frac{\cos\left(x\right)-\sin\left(x\right)}{\cos\left(x\right)+\sin\left(x\right)}$

$\int xsenx\sqrt[4]{e^x}dx$