Question

The angle elevation of an aero plane from A on the ground is 60°. After 15seconds
flight, the angle of elevation changes to 30".If the aero plane is flying at a height of 3000m,
find the speed of the plane

Answer 1

Answer:

Height of aeroplane =BD=CE=15003 m and 

∠BAE=600 and CAE=300

In triangle ADB

tan600=AD15003

⇒3=AD15003

⇒AD=1500 m

In triangle CAE 

tan300=AE15003

⇒31=AD15003

⇒AE=1500×3=4500 m

Distance covered by plane in 15 seconds: BC=DE=AE−AD=4500−1500=3000 m

Speed of aeroplane =153000=200 m/s=720 km/hr

Hope it will help you dear........