A plane passes directly over your head at an altitude of 500 feet. Two seconds later you observe that the angle of elevation of the plane is 42 degrees. How far did the plane travel during those two seconds?
Let point A be the point the plane initially was and C the point directly below the plane. Say the plane travels from point A to the point B in two seconds. Then that the angle formed by AC and CB is the angle of elevation.
The angle of elevation is given as 42 degrees. So tan 42 = AB/AC = AB/ 500