Write 'True' or 'False' and justify your answer.
The angle of elevation of the top of a tower is $30^{\circ}$. If the height of the tower is doubled,then the angle of elevation of its top will also be doubled.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(FALSE) False.
$Case-I$: Let the height of the tower be $h$ and the distance from the base be $BC = x \ m$.
In $\triangle ABC$,$\tan 30^{\circ} = \frac{AC}{BC} = \frac{h}{x}$.
$\frac{1}{\sqrt{3}} = \frac{h}{x} \implies h = \frac{x}{\sqrt{3}}$ ... $(i)$
$Case-II$: By the given condition,the height of the tower is doubled,i.e.,$h' = 2h$.
Let the new angle of elevation be $\theta$.
In the new triangle,$\tan \theta = \frac{h'}{x} = \frac{2h}{x}$.
Substituting $h = \frac{x}{\sqrt{3}}$ from $(i)$:
$\tan \theta = \frac{2(x/\sqrt{3})}{x} = \frac{2}{\sqrt{3}} \approx 1.1547$.
Since $\tan 60^{\circ} = \sqrt{3} \approx 1.732$,and $\tan \theta \approx 1.1547 < 1.732$,it follows that $\theta < 60^{\circ}$.
Thus,the angle of elevation is not doubled.

Explore More

Similar Questions

The angle of elevation of the top of the tower from a point $x \, m$ away from the tower is $30^{\circ}$. Then the height of the tower is $\ldots \ldots \ldots \, m$.

Watching from a point on the ground $20 \, m$ away from the base of an erect pole,the angle of elevation of the top of the pole is found to be $45^{\circ}$. Then,the height of the pole is $\ldots \ldots \ldots \, m$.

Observing from the top of a building,the angle of elevation of the top of a tower is $30^{\circ}$ and the angle of depression of the base of the tower is $60^{\circ}$. If the height of the building is $36 \, m$,find the height of the tower (in $m$).

Difficult
View Solution

Two boats are anchored in the same direction from a $100 \, m$ high lighthouse. The angles of depression of the boats from the top of the lighthouse are $30^{\circ}$ and $45^{\circ}$. Find the distance between these two boats (in $m$).

$A$ cable tied to the top of an electric pole is fixed at a point on the ground. The length of the cable is $22\, m$ and it makes an angle of measure $30^{\circ}$ with the ground. Find the height of the electric pole (in $m$).

Difficult
View Solution

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo