At an airshow, a pilot is flying low over a runway while maintaining a constant altitude of 2000 feet and a constant speed. On a straight path over the runway, the
pilot observes on her laser range-finder that the distance from the plane to a fixed
building adjacent to the runway is 7500 feet. Five seconds later, she observes that
the distance to the same building is now 6000 feet.
a. What is the angle of depression from the plane to the building when the
plane is 7500 feet away from the building? (The angle of depression is the
angle that the pilot's line of sight makes with the horizontal.)
b. What is the angle of depression when the plane is 6000 feet from the
building?
c. How far did the plane travel during the time between the two different
observations?
d. What is the plane's velocity (in miles per hour)?