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JEE Main20198 Apr 2019Evening ShiftMathematicsHeights and DistancesActual

Two vertical poles of height, 20 m and 80 m stand apart on a horizontal plane. The height (in meters) of the point of intersection of the lines joining the top of each pole to the foot of the other, from this horizontal plane is:

Options

  1. A16
  2. B12
  3. C18
  4. D15

Correct answer

A. 16

Step-by-step solution

Equation of line O Q y = 80 a x Equation of line A B x a + y 20 = 1 Solving for P x 0 , y 0 , a y 0 / 80 a + y 0 20 = 1 ⇒ y 0 1 80 + 1 20 = 1 ⇒ y 0 = 16

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