Answer
a) $θ=$tan$^{-1}(\frac{50}{s})$
b) 1.2 radians
Work Step by Step
a) Since the sides that are marked belong to the legs of the triangle, the trigonometric function that works here is tangent. Tangent is opposite over adjacent. So,
tan $θ=(\frac{50}{s})$
solving for θ gives:
$θ=$tan$^{-1}(\frac{50}{s})$
b) using the equation found before, we substitute $s$ for $20$:
$θ=$tan$^{-1}(\frac{50}{20})$
$θ=$tan$^{-1}(2.5)$
$θ\approx1.2$ radians
