Evaluate: $\sec^{-1} x + \operatorname{cosec}^{-1} x + \cos^{-1}(x^{-1}) + \sin^{-1}(x^{-1})$ (where $|x| > 1, x \in R$)

$2 \pi - \left(\sin ^{-1} \frac{4}{5} + \sin ^{-1} \frac{5}{13} + \sin ^{-1} \frac{16}{65}\right)$ is equal to

If $(\tan^{-1} x)^2 + (\cot^{-1} x)^2 = \frac{5\pi^2}{8}$, then the value of $x$ is equal to...

If ${\tan ^{ - 1}}x - {\tan ^{ - 1}}y = {\tan ^{ - 1}}A,$ then $A$ is equal to:

Evaluate: $\tan ^{ - 1}\left(\frac{{{c_1}x - y}}{{{c_1}y + x}}\right) + \tan ^{ - 1}\left(\frac{{{c_2} - {c_1}}}{{1 + {c_2}{c_1}}}\right) + \tan ^{ - 1}\left(\frac{{{c_3} - {c_2}}}{{1 + {c_3}{c_2}}}\right) + ... + \tan ^{ - 1}\left(\frac{1}{{{c_n}}}\right)$

$2{\tan ^{ - 1}}\frac{1}{3} + {\tan ^{ - 1}}\frac{1}{2} = $