An observer is 20m above the ground floor of a large hotel atrium looking at a glass-enclosed elevator shaft that is 20m horizontally from the observer. the angle of elevation of the elevator is the angle that the observer's line of sight makes the horizontal. assuming that the elevator rises at a rate of 5 meters a second what is the rate of change of the angle of elevation on the elevator 10 meters above the ground? (list steps with answer if possible)