Question

A building 15 m high casts a shadow 1.8 m long. What will be height of that pole whose shadow at that time in 60 cm?

Answer 1

Given that,

A $15m$ high building casts a $1.8m$ long shadow.

Shadow of a pole at the same time is $60cm$.

To find out,

The height of the pole.

Let the height of the pole be $h$.

In both the cases, the angle of elevation of Sun will be the same.

Let the angle be $\theta$.

Hence, $\tan \theta =\frac{\text{Height of the building}}{\text{Length of its shadow}}=\frac{\text{Height of the Pole}}{\text{Length of its shadow}}$

The length of the shadow is $60cm$.

We know that $100cm=1m$

$\therefore 60cm=0.6m$

Hence, $\frac{h}{0.6}=\frac{15}{1.8}$

$\Rightarrow h=\frac{15\times 0.6}{1.8}$

$\Rightarrow h=\frac{9}{1.8}$

$\therefore h=5m$

Hence, the height of the pole is $5m$.