$-\frac{\left|\operatorname{cosec} \frac{x}{2}\right|}{2 \sqrt{\sin ^2 \frac{x}{2}-\cos ^2 \frac{x}{2}}}$

$\frac{\left|\sec \frac{x}{2}\right|}{2 \sqrt{\cos x}}$

$\frac{\cos \frac{x}{2}}{2 \sqrt{\cos x}}$

$\frac{\cos \frac{x}{2}}{\sqrt{\cos x}}$

$\tan \frac{\theta}{3}$

$\frac{1}{3} \tan \theta$

$\tan 3 \theta$

$\frac{1}{3} \tan 3 \theta$

$\frac{1}{6}$

$\frac{1}{20}$

6

20

$\frac{4}{16 x^2+1}-\frac{3}{9 x^2+1}$

$\frac{3}{9 x^2+1}-\frac{1}{x^2+1}$

$\frac{3}{9 x^2+1}-\frac{2}{4 x^2+1}$

$\frac{1}{9 x^2+1}-\frac{1}{x^2+1}$