Answer
$\theta=\sin^{-1} (\dfrac{opposite}{hypotenuse})$
Work Step by Step
The trigonometric ratios are as follows:
$ \sin \theta =\dfrac{opposite}{hypotenuse} $
Suppose $\theta =\sin^{-1} [\dfrac{opposite}{hypotenuse} ]$
Now, $\sin \theta =\sin [\sin^{-1} (\dfrac{opposite}{hypotenuse})]$
Thus, we have $\theta=\sin^{-1} (\dfrac{opposite}{hypotenuse})$
