Answer
$48 feet $
Work Step by Step
The trigonometric ratios are as follows: $\sin \theta= \dfrac{opposite}{hypotenuse}$ ; $\cos \theta= \dfrac{Adjacent}{hypotenuse}$ and $\tan \theta= \dfrac{Opposite}{Adjacent}$
$ h_1=(75+a) \tan 20^{\circ}$ and $ h_1= a \tan 40^{\circ}$
Now, $ a =\dfrac{75 \times \tan 20^{\circ}}{\tan 40^{\circ}-\tan 20^{\circ}}=57.45$
and $ h_1= 57.45 \times \tan 40^{\circ}=48 feet $
