Answer
$\dfrac{\pi}{4}$
Work Step by Step
We need to find $\tan^{-1} (1) $
The inverse tangent function has the range $-\dfrac{\pi}{2} \leq \theta \leq \dfrac{\pi}{2}$. We are looking for the angle whose tangent value equals $1$.
Since, $\dfrac{\pi}{4}$ lies in $-\dfrac{\pi}{2} \leq \theta \leq \dfrac{\pi}{2}$, then we have:
$\tan^{-1} (1) =\dfrac{\pi}{4}$
