trigonometry
posted by ann .
An airbus A320 aircraft is cruising at an altitude of 10000 m. The aircraft is flying in a straight line away from Rachel, who is standing on the ground. If she sees the angle of elevation of the aircraft change from 70 degrees to 33 degrees in one minute, what is its cruising speed, to the nearest kilometer per hour?

The distance the airplane covers in that time is 10 km * (cot 33  cot 70). Divide that by the time (1/60 h)
D = 15.3986  3.6397 = 11.759 km
V = ____ km/h