$sin\left(\frac{12}{13}+\left(-\frac{\sqrt{5}}{5}\right)\right)$

$sin\left(2\arccos\left(x\right)\right)=2x\sqrt{1-x^2}$

$\lim_{x\to-0.01}\left(\frac{2x^2-7x+3}{x}\right)$

$\left(\sec\left(a\right)-1\right)\left(\sec\left(a\right)+1\right)$

$\frac{1}{\cos\left(x\right)}=\frac{sinx}{cosx}+\frac{cosx}{1+sinx}$

$\frac{d^2}{dx^2}\left(y=\frac{1}{2}\cdot x^4-5x^3+12x^2\right)$

$\lim_{x\to-1}\left(\frac{x^2-x+2}{x^2+2x+1}\right)$