Question
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 travelled by the balloon during the interval.
Fig. 9.13.
Solution
In right triangle EAG, we have
In right triangle FAC, we have
In right triangle FAC, we have
⇒ Distance travelled by the balloon
EF = GC = AC - AG
= (150.68 - 50.23) m
= 100.45 metres.
