Two poles of equal heights are standing opposite to each other on either side of the
Two poles of equal heights are standing opposite to each other on either side of the road which is 80 m wide. From a point between them on the road the angles of elevation of the top of the poles are 60° and 30° respectively. Find the height of the poles and the distance of the point from the poles.
Let
and
be the two poles of equal height h m.
be the points makes an angle of elevation from the top of poles are 60° and 30° respectively.
Let $O A=80-x, O D=x .$ And $\angle B O A=30^{\circ}, \angle C O D=60^{\circ}$.
Here we have find height of poles and distance of the points from poles.
We have the corresponding figure as follows.

So we use trigonometric ratios.
In a triangle
,
$\Rightarrow \quad \tan 60^{\circ}=\frac{C D}{D O}$
$\Rightarrow \quad \sqrt{3}=\frac{h}{x}$
$\Rightarrow \quad x=\frac{h}{\sqrt{3}}$
Again in a triangle
,
$\Rightarrow \quad \tan 30^{\circ}=\frac{A B}{O A}$
$\Rightarrow \quad \frac{1}{\sqrt{3}}=\frac{h}{80-x}$
$\Rightarrow \quad \sqrt{3} h=80-x$
$\Rightarrow \quad \sqrt{3} h=80-\frac{h}{\sqrt{3}}$
$\Rightarrow \sqrt{3} h+\frac{h}{\sqrt{3}}=80$
$\Rightarrow \quad 3 h+h=80 \sqrt{3}$
$\Rightarrow \quad 4 h=80 \sqrt{3}$
$\Rightarrow \quad h=20 \sqrt{3}$
$\Rightarrow \quad x=\frac{20 \sqrt{3}}{\sqrt{3}}$
$\Rightarrow \quad=20$
And
$\Rightarrow \quad O A=80-x$
$\Rightarrow \quad=80-20$
$\Rightarrow \quad=60$
Hence the height of pole is $20 \sqrt{3} \mathrm{~m}$. and distances are $20 \mathrm{~m}, 60 \mathrm{~m}$ respectively.