Answer
$\dfrac{\pi}{2}$
Work Step by Step
We need to find:
$\cos^{-1}(0)$
The inverse cosine function has the domain $0\le \theta \le \pi$. We are looking for the angle whole cosine value equals zero.
We know from the unit circle that
$\cos (\dfrac{\pi}{2})=0$
Since $\frac{\pi}{2}$ lines in the domain $0\le \theta \le \pi$, then we have:
$\cos^{-1}(0)=\dfrac{\pi}{2}$
