$\frac{sin\left(x\right)-cos\left(x\right)}{sin\left(x\right)}=\frac{cos\left(x\right)-sin\left(x\right)}{cos\left(x\right)}$

$9 ( 5 v - 3 ) + 4 ( 2 v + 5 )$

$cos^2x-cos2x=sin^2x$

$20\:+\:0,5xi\:+\:0,1xi\:2\:$

$\frac{2\sec\left(x\right)}{\tan\left(^2\right)x}$

$\frac{x^2-5x-6}{3x^2}$

$\lim_{x\to1}\left(\frac{1-\cos.\left(x-1\right)}{\left(\ln\left(x\right)\right)^2}\right)$