Trigonometric Equations Question 129
Question: The angle of elevation of the top of a tower at point on the ground is $ 30^{o} $ . If on walking 20 metres toward the tower, the angle of elevation become $ 60^{o} $ , then the height of the tower is
[MNR 1975; IIT 1967]
Options:
A) 10 metre
B) $ \frac{10}{\sqrt{3}}metre $
C) $ 10\sqrt{3}metre $
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
- $ OA=h,\cot 60^{o},,OB=h\cot 30^{o} $ , $ R=\frac{abc}{4\Delta } $
$ \Rightarrow $ $ h=\frac{20}{( \sqrt{3}-\frac{1}{\sqrt{3}} )}=\frac{20\sqrt{3}}{2}=10\sqrt{3} $ .
BETA
