The angle of elevation of the top of a building from a point on the ground, which is 30 m away from the foot of the building, is 30°. The height of the building is:
Say x is the height of the building.
a is a point 30 m away from the foot of the building.
Here, height is the perpendicular and distance between point a and foot of building is the base.
The angle of elevation formed is 30°.
Hence, tan 30° = $\dfrac{perpendicular}{base}$ = $\dfrac{x}{30}$
$\dfrac{1}{\sqrt{3}}$ = $\dfrac{x}{30}$
x =$ \dfrac{30}{\sqrt{3}}$