JEE Main & Advanced
Mathematics
Trigonometric Equations
Question Bank
Height and Distance
question_answer
An observer on the top of a tree, finds the angle of depression of a car moving towards the tree to be 30oo. After 3 minutes this angle becomes 60o. After how much more time, the car will reach the tree
A)4 min.
B)4.5 min.
C)1.5 min.
D)2 min.
Correct Answer:
C
Solution :
\[d=h\cot {{30}^{o}}-h\cot {{60}^{o}}\text{ and time }=\]3 min. \[\therefore \] Speed = \[\frac{h(\cot {{30}^{o}}-\cot {{60}^{o}})}{3}\] per minute It will travel distance \[h\cot {{60}^{o}}\] in \[\frac{h\cot {{60}^{o}}\times 3}{h(\cot {{30}^{o}}-\cot {{60}^{o}})}\] = 1.5 minute.