$1+sec^{\left(2\right)}\theta\:\cdot sin^{\left(2\right)}\theta\:=sec^{\left(2\right)}\theta\:$

$z=x^2sen\left(\frac{x}{y}\right)$

$-6\sqrt{5}9\sqrt{5}$

$\lim_{x\to\infty}\left(\frac{2x}{x^2-4}\right)$

$tan\left(\frac{1}{4}x\right)=1$

$x^2=y^2+c$

$\sin^2\theta+\sin\theta-2=0$