Answer
$\dfrac{\pi}{6}$
Work Step by Step
Suppose $\theta =\sin (\dfrac{5\pi}{6})$
This gives: $\sin^{-1} \theta=\sin^{-1}[\sin(\dfrac{5\pi}{6})]$
The inverse property states that $\sin^{-1}(\sin a)=a $ satisfies for every $ a $ in the range $[-\dfrac{\pi}{2},\dfrac{\pi}{2}]$ .
Therefore, we have $\sin^{-1}[\sin(\dfrac{5\pi}{6})]=\dfrac{\pi}{6}$
