JEE Mains · Maths · STD 11 - Trigonometrical equations
A man is walking towards a vertical pillar in a straight path, at a uniform speed. At a certain point \(A\) on the path, he observes that the angle of elevation of the top of the pillar is \(30^o .\) After walking for \(10\) minutes from \(A\) in the same direction, at a point \(B,\) he observes that the angle of elevation of the top of the pillar is \(60^o .\) Then the time taken (in minutes) by him, from \(B\) to reach the pillar, is:
- A \(20\)
- B \(5\)
- C \(6\)
- D \(10\)
Answer & Solution
Correct Answer
(B) \(5\)
Step-by-step Solution
Detailed explanation
Let \(PQ\) represent pillar. Say height \(=\,h\) In \(\Delta PAQ,\,\,\tan \,{30^o}\, = \frac{{PQ}}{{AQ}}\) \( \Rightarrow \,AQ\, = \,\sqrt 3 h\) In \(\Delta PQB,\,\,\tan \,{60^o}\, = \frac{{PQ}}{{BQ}} \Rightarrow BQ\, = \,\frac{h}{{\sqrt 3 }}\) Now, the person is walking at a…
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