$\frac{sinx}{1+cosx}=1-\frac{cosx}{sinx}$

$\frac{dy}{dx}=\frac{x}{y^2},\:y\left(2\right)=3$

$\frac{dx}{dx}+y\cot\left(x\right)=5e^{\cos\left(x\right)}$

$cos^2=cos2$

$2xy+xy-x$

$\left(5n\right)\left(-4n^2\right)$

$\frac{1}{\cos\left(x\right)\left(1+\frac{\sin\left(x\right)^2}{\cos\left(x\right)^2}\right)}$