$\left(cos\left(\frac{\pi}{2}-b\right)cosb\right)-\left(sin\left(\frac{\pi}{2}-b\right)sinb\right)$

$\lim_{x\to0}\left(xln\left(1-\cos\:\left(x\right)\right)\right)$

$\left(-2\right)^2-3\left(-2\right)+1$

$0.00027+0.00098+0.00132+0.00109+0.00418$

$\lim_{x\to0.999}\left(\frac{2x^2-x-1}{x-1}\right)$

$\int\frac{x^2-2x-1}{x^2+1}dx$

$\frac{1}{2}\int\frac{1}{2}seczdz$