An aircraft is flying at a height of 3400m above the ground. If the angle subtended at a ground observation point by the aircraft positions 10 s apart in 30o , what is the speed of the aircraft?

The aircraft takes 10s to go from A to B and AB subtends an angle 30^{o} at O.

In right angled triangle OAC,

AC = OC tan 15^{o} = 3400 x 0.2679 = 911 m

Therefore, AB = 2 x 911 = 1822 m

Now, the speed of aircraft

v = AB/t = 1822 / 10 = 182.2 m/s