Q. 144.4( 238 Votes )
A 1.2 m tall girl spots a balloon moving with the wind in a horizontal line at a height of 88.2 m from the ground. The angle of elevation of the balloon from the eyes of the girl at any instant is 60°. After some time, the angle of elevation reduces to 30° (see Fig. 9.13).Find the distance traveled by the balloon during the interval.
From this figure:
BF = height of girl = 1.2 m,
AG = height of balloon from ground initially = 88.2 m,
AC = AG – GC
= 88.2 – 1.2
= 87 m
∠EBD = 30° and ∠ABC = 60°,
CD = ?
In Δ ABC;
where p = perpendicular and b is base
In Δ ABC,
Now, the distance covered by the balloon will be:
CD = BD – BC
CD = 58√3 m
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