$\lim_{x\to\frac{\pi}{2}}\left(\left(x-\frac{\pi}{2}\right)\cdot tanx\right)$

$2\sec^2x\left(1-\sin^2x\right)$

$\lim_{n\to\infty}\left(\frac{sin\:n\pi}{n}\right)$

$\frac{x^{3}y^{2}}{xy}=i$

$\lim_{x\to6}\left(\frac{x^2-6x}{x^2-7x-6}\right)$

$\left(\frac{2}{3}m\right)\left(-3m^2+6n+1\right)$

$w=\frac{\text{sen}^4\theta-\cos^4\theta+1}{1+\cot g^2\theta}$