The principal value of $cot^{-1}\left(\frac{-1}{\sqrt{3}}\right)$ is :
Answer & explanation
Correct answer: option 2
The correct answer is option (2) → $\frac{2\pi }{3}$
$\cot^{-1}\left(\frac{-1}{\sqrt{3}}\right)=\pi - \cot^{-1}\left(\frac{1}{\sqrt{3}}\right)$
$\pi - \frac{\pi}{3}=\frac{2\pi}{3}$