Answer
$214.5 \ ft$
Work Step by Step
The trigonometric functions can be expressed as:
$\sin \theta=\dfrac{Opposite}{Hypotenuse} \\ \cos \theta=\dfrac{Adjacent}{Hypotenuse} \\ \tan \theta=\dfrac{Opposite}{Adjacent}$
We are given the angle and the opposite side. Our aim is to compute the adjacent side. So we use tangent.
Let $a$ be the adjacent side.
Since, $\tan \theta=\dfrac{Opposite}{Adjacent}$
Therefore, $\tan (25^{\circ})=\dfrac{100}{a} \implies a \approx 214.5 \ ft$
