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JEE Main201912 Jan 2019Evening ShiftMathematicsHeights and DistancesActual

If the angle of elevation of a cloud from a point P which is 25 m above a lake be 30 o and the angle of depression of reflection of the could in the lake from P be 60 o , then the height of the cloud (in meters) from the surface of the lake is :

Options

  1. A50
  2. B60
  3. C45
  4. D42

Correct answer

A. 50

Step-by-step solution

tan ⁡ 30 o = x - 25 d and tan ⁡ 60 o = x + 25 d ⇒ tan ⁡ 30 o tan ⁡ 60 o = x - 25 x + 25 ⇒ 1 3 = x - 25 x + 25 ⇒ x + 25 = 3 x - 75 ⇒ 2 x = 100 ⇒ x = 50 m

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