Q194 / 270 · NDA 2011 (Phase 2) · Mathematics
A tower of height 15 m stands vertically on the ground. From a point on the ground the angle of elevation of the top of the tower is found to be $30^{\circ}$. What is the distance of the point from the foot of the tower?
- Correct answerA$15 \sqrt{3} \mathrm{~m}$
- B$10 \sqrt{3} \mathrm{~m}$
- C$5 \sqrt{3} \mathrm{~m}$
- D30 m
Solution
Let $A B$ is tower

$\begin{aligned} \tan 30^{\circ} & =\frac{15}{x} \\ \frac{1}{\sqrt{3}} & =\frac{15}{x}\end{aligned}$ $x=15 \sqrt{3}$ $\therefore$ Distance of the point from the foot of the tower is $15 \sqrt{3} \mathrm{~m}$.

$\begin{aligned} \tan 30^{\circ} & =\frac{15}{x} \\ \frac{1}{\sqrt{3}} & =\frac{15}{x}\end{aligned}$ $x=15 \sqrt{3}$ $\therefore$ Distance of the point from the foot of the tower is $15 \sqrt{3} \mathrm{~m}$.
Hence, the correct answer is option: 'A'.