Question:
From a point on the ground, 20 m away from the foot of a vertical tower, the angle elevation of the top of the tower is 60°, What is the height of the tower?
Solution:
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 $20 \sqrt{3}$.