What will be the Length of Poll (in meter)? If

From two points on the ground and lying on a straight line through the foot of a pillar, the two angles of elevation of the top of the pillar are complementary to each other. If the distances of the two points from the foot of the pillar are 12 metres and 27 metres and thw two points lie on the same side of the pillar, then the leight (in metres) of the pillar is:

  1. 16
  2. 12
  3. 15
  4. 18
Monis Rasool Professor Asked on 8th July 2015 in Maths.
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    Answer: (4) 18 m
    Explanation:-
    Let be the height of the pillar = h
    According to the question,
    Let be the angles are X and (90 – X)
    In the figure-

    RE: What will be the Length of Poll (in meter)? If


    tan (90 – X) = h/27                                        (tan (90 – X) = Cot X)
    Cot X = h/27                         ……… (1)
    And
    tan X = h/12                                                       (tan X = 1/Cot X)
    Cot X = 12/h                                    ….. (2)
    Comparing equation (1) & (2)
    h/27 = 12/h
    h2 = 27 x 12
    h2  = 324
    quare root on both side
    h = 18 m
    Hence, the height of the pillar is 18 m.

    Anurag Mishra Professor Answered on 14th July 2015.
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