Trigonometric Equations Question 79
Question: The angle of elevation of the top of a pillar at any point A on the ground is $ 15^{o} $ . On walking 40 metres towards the pillar, the angle become $ 30^{o} $ . The height of the pillar is
[MP PET 2001]
Options:
A) 40 metres
B) 20 metres
C) $ 20\sqrt{3}metres $
D) $ \frac{40}{3}\sqrt{3}metres $
Show Answer
Answer:
Correct Answer: B
Solution:
- Let h be the height of pillar $ OB=h\cot 30^{o} $ and $ OA=h\cot 15^{o} $
Þ $ AB=OA-OB=h(\cot 15^{o}-\cot 30^{o}) $
Þ $ ,h=\frac{40}{\cot 15^{o}-\cot 30^{o}} $ = 20 metre.
BETA
