Question

Evaluate ${\cos }^{-1}\left(0\right)$

Answer 1

Let $\alpha$ is an angle equal to ${\cos }^{-1}\left(0\right)$
$\alpha ={\cos }^{-1}\left(0\right)$
We know that, $\cos 90°=0$
$$\begin{gathered} \therefore \alpha ={\cos }^{-1}(\cos 90°) \\ \alpha ={\cos }^{-1}\left(0\right) \\ \alpha =\frac{\pi }{2} \end{gathered}$$

Hence, ${\cos }^{-1}\left(0\right)$ is $\frac{\pi }{2}$.