Answer
$s=\dfrac{\pi}{4}$
Work Step by Step
RECALL:
$\frac{\pi}{4}$ is a special angle and $\cos{(\frac{\pi}{4})}=\dfrac{\sqrt2}{2}$
Thus, if $\cos{s} = \frac{\sqrt2}{2}$, then $s=\dfrac{\pi}{4}$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.