Answer
$\theta=\arctan (\dfrac{s}{750}) $ or, $\theta=\tan^{-1} (\dfrac{s}{750})$
Work Step by Step
We will take the tangent of an angle.
That is, $\tan \theta =\dfrac{s}{750}$
Now, take the inverse of the tangent of an angle.
$\theta=\arctan (\dfrac{s}{750}) $ or, $\theta=\tan^{-1} (\dfrac{s}{750})$
Plug in the data to obtain:
$\theta=\arcsin (\dfrac{5}{40})=0.125 $
and
$\theta=\arcsin (\dfrac{5}{20})=0.253 $
