A spherical gas balloon of radius 16 meter subtends an angle 60 ° at the eye of the observer A while…

A spherical gas balloon of radius 16 meter subtends an angle 60° at the eye of the observer A while the angle of elevation of its center from the eye of A is 75°. Then the height (in meter) of the top most point of the balloon from the level of the observer's eye is :
  1. 8(2+23+2)
  2. 8(6+2+2)
  3. 8(2+2+3)
  4. 8(6-2+2)

Solution

Assume, O is the  centre of sphere

and P,Q are the point of contact of tangents from A

Let T be top most point of balloon & R be foot of perpendicular from O to ground.

From triangle OAP, sin30°=16OA

OA=16cosec30°=32

From triangle ARO, sin75°=OROA

OR=OAsin75°

32(3+1)22=86+82

So the height (in meter) of the top most point of the balloon from the level of the observer's eye is OR+OT

=8(6+2+2)

Asked in: JEE Main 2021 (25 Jul Shift 1)

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