[T] A building that is 225 feet tall casts a shadow of various lengths
as the day goes by. An angle of elevation
is formed by lines from the top and bottom of the building to the tip of the shadow, as seen in the following figure. Find the rate of change of the angle of elevation
when
feet.
[T] A pole stands 75 feet tall. An angle
is formed when wires of various lengths of
feet are attached from the ground to the top of the pole, as shown in the following figure. Find the rate of change of the angle
when a wire of length 90 feet is attached.
[T] A television camera at ground level is 2000 feet away from the launching pad of a space rocket that is set to take off vertically, as seen in the following figure. The angle of elevation of the camera can be found by
where
is the height of the rocket. Find the rate of change of the angle of elevation after launch when the camera and the rocket are 5000 feet apart.
[T] A local movie theater with a 30-foot-high screen that is 10 feet above a person’s eye level when seated has a viewing angle
(in radians) given by
where
is the distance in feet away from the movie screen that the person is sitting, as shown in the following figure.
Find
Evaluate
for
and 20.
Interpret the results in b..
Evaluate
for
and 40
Interpret the results in d. At what distance
should the person stand to maximize his or her viewing angle?
a.
b.
c. As a person moves farther away from the screen, the viewing angle is increasing, which implies that as he or she moves farther away, his or her screen vision is widening. d.
e. As the person moves beyond 20 feet from the screen, the viewing angle is decreasing. The optimal distance the person should stand for maximizing the viewing angle is 20 feet.