MathematicsTwo ships are sailing in the sea on the two sides of a lighthouse.The angles of elevation of the top of the lighthouse as observed from the two ships are 30°and 45°respectively. If the lighthouse is 100 m high the distance between the two ships is

Two ships are sailing in the sea on the two sides of a lighthouse.


The angles of elevation of the top of the lighthouse as observed from the two ships are 30°and 45°respectively. If the lighthouse is 100 m high the distance between the two ships is


  1. A
    173m
  2. B
    200m
  3. C
    273m
  4. D
    300m  

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    Solution:

    It is given that the angles of elevation of the top of the lighthouse are 30°and 45°,observed from the two ships, and the lighthouse is 100 m in height.
    According to the given data, the figure has been drawn below.
    Let AB be the height of lighthouse and and be the position of the ships.
    Given, AB=100 m and ACB=30° ADB=45°.
    In ΔBCA,
      tanθ= Perpendicular base  
    ABAC=tan30°
    ABAC=13 tan30°=13
     AC=3AB
    AC=1003
    In ΔBAD, tanθ= Perpendicular base  
    ABAD=tan45° ABAD=1 tan45°=1
    AD=AB=100m CD=AC+AD 1003+100 100(3+1) 100(1.73+1)    3=1.732
    273 m Distance between the two ships is 273m.
    So, the correct option is 3.
     
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