$\cos\left(x\right)=.2145$

$\sin\left(180+x\right)-\cos\left(90-x\right)-\sin\left(-x\right)=-\sin\left(x\right)$

$m\:+\:15\:<35$

$\frac{x^5}{x^4-1}$

$\frac{-1}{u}=\frac{u+5}{6}$

$\csc\left(x\right)^4-8\cot\left(x\right)^2+\csc\left(x\right)\cdot\cot\left(x\right)^2$