20
Chapter 1
•
Right Triangle Trigonometry
§1.3
Exercises
150
h
12
◦
34
◦
1.
From a position 150 ft above the ground, an observer in a build
ing measures angles of depression of 12
◦
and 34
◦
to the top and
bottom, respectively, of a smaller building, as in the picture on
the right. Use this to ±nd the height
h
of the smaller building.
h
b
a
β
α
2.
Generalize Example 1.12: A person standing
a
ft from the base of
a mountain measures an angle of elevation
α
from the ground to
the top of the mountain. The person then walks
b
ft straight back
and measures an angle of elevation
β
to the top of the mountain,
as in the picture on the right. Assuming the ground is level, ±nd
a formula for the height
h
of the mountain in terms of
a
,
b
,
α
,
and
β
.
3.
As the angle of elevation from the top of a tower to the sun decreases from 64
◦
to 49
◦
during the
day, the length of the shadow of the tower increases by 92 ft along the ground. Assuming the
ground is level, ±nd the height of the tower.
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 Fall '11
 Dr.Cheun
 Calculus, Trigonometry, Angles, smaller building

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