A balloon is moving up in air vertically above a point A on the ground. When it is a height h 1 , a girl…

A balloon is moving up in air vertically above a point A on the ground. When it is a height h1, a girl standing at a distance d (point B) from A (see figure) sees it at an angle 45° with respect to the vertical. When the balloon climbs up a further height h2, it is seen at an angle 60° with respect to the vertical if the girl moves further by a distance 2.464 d (point C). Then the height h2 is (given tan30°=0.5774):

  1. 1.464 d
  2. 0.732 d
  3. 0.464 d
  4. d

Solution

t45=h1d

h1=d   .......(i)

h1+h2d+2.464d=tan30°=13=0.5774

h1+h2=(3.464)d×0.5774

h1+h2=2d   .......(ii)

  h2=d

 

Asked in: JEE Main 2020 (05 Sep Shift 1)

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