A 2.2m tall girl spots an aeroplane moving with the wind in a horizontal line at a height of 86.2m from the ground. The angle of elevation of the aeroplane from eyes of the girl at instant is 60°. After some time, the angle of elevation reduces to 30°. Find the distance travelled by the aeroplane during the interval?
(a) 84√3 m
(b) 56√3m
(c) 70√3m
(d) 56m
Sol:
In ∆ ACD
AD = 84m
tan60° =AD/CD
