Question

the angle of elevation of a jet plane from a point a on the ground is 60 degree after a flight of 15 seconds the angle of elevation changes to 30 degrees if the jet plane is flying at a constan height of of 14500 root 3 metre find the speed of the plane​

Answer 1

In triangle AEB,

tan 60 = EB/ AB

√3 = 14500√3/AB

AB = 14500√3/√3 = 14500m

Now,

In triangle ADC,

tan 30 = DC/AC ⇒ tan 30 = DC/ AB+BC

1/√3 = 14500√3/ 14500+BC

14500 + BC = 14500√3 × √3 = 14500 × 3 = 43500

∴ BC = 43500 - 14500

∴ BC = 29000m

Speed = Distance/ Time

            = 29000/15

            = 1933.33 m/s or 5800/3 m/s