Answer
$\frac{\pi}{6}$
Work Step by Step
Letting $sec^{-1}(\frac{2}{\sqrt 3})=t, 0\lt t \lt \pi$, we have $sec(t)=\frac{2}{\sqrt 3}$
Thus $cos(t)=\frac{\sqrt 3}{2}$ and $t=\frac{\pi}{6}$
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.