From a point on the ground, 20 m away from the foot of a vertical tower

Let  be the height of tower is meters.

Given that: angle of elevation is and  meters.

Here we have to find height of tower.

So we use trigonometric ratios.

In a triangle,

$\Rightarrow \tan C=\frac{A B}{B C}$

$\Rightarrow \tan 60^{\circ}=\frac{h}{20}\left[\because \tan 60^{\circ}=\sqrt{3}\right]$

$\Rightarrow \sqrt{3}=\frac{h}{20}$

$\Rightarrow h=20 \sqrt{3}$

Hence height of tower is $20 \sqrt{3}$.