Trigonometric Equations Question 133
Question: A person standing on the bank of a river observes that the angle subtended by a tree on the opposite bank is 60°. When he retires 40 meters from the bank, he finds the angle to be $ 30^{o} $ . The breadth of the river is
[IIT 1975; AIEEE 2004]
Options:
A) 20 m
B) 40 m
C) 30 m
D) 60 m
Show Answer
Answer:
Correct Answer: A
Solution:
- $ b=h\cot 60^{o},,b+40=h\cot 30^{o} $
$ \Rightarrow $ $ \frac{b}{b+40}=\frac{\cot 60^{o}}{\cot 30^{o}} $
$ \Rightarrow $ $ b=20m $ .
BETA
