A 1.2 m tall girl spots a balloon movingwith the wind in a horizontal line at aheight of 88.2 m from the ground. Theangle of elevation of the balloon fromthe eyes of the girl at any instant is60°. After some time, the angle ofelevation reduces to 30° (see Fig. 9.13).Find the distance travelled by theballoon during the interval.

Question

Philoid · Accepted Answer

From this figure:

BF = 1.2 m,

AG = 88.2 m,

AC = AG – GC

= 88.2 – 1.2

= 87 m

∠EBD = 30° and ∠ABC = 60°,

CD = ?

In Δ ABC;

In Δ ABC,

Now, the distance covered by the balloon will be:

CD = BD – BC

CD =

CD = 5