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Chapter 9 Lesson 3

• Objective To use angles of elevation and
  depression to solve problems.

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Angle of Elevation
An angle of elevation is the angle formed by a
horizontal line and the line of sight to an
object above the horizontal line.
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Angle of Depression
An angle of depression is the angle formed by a
horizontal line and the line of sight to an
object below the horizontal line.
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(No Transcript)
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Example 1 Identifying Angles of Elevation and
Depression
Describe each angle as it relates to the
situation shown
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Example 2 Real-World Connection
Surveying To find the height of Delicate Arch in
Arches National Park in Utah, a surveyor levels a
theodolite with the bottom of the arch. From
there, she measures the angle of elevation to the
top of the arch. She then measures the distance
from where she stands to a point directly under
the arch. Her results are shown in the diagram.
What is the height of the arch?
So x 40. To find the height of the arch, add
the height of the theodolite. Since 40 5 45,
Delicate Arch is about 45 feet high.
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Example 3 Real-World Connection
Aviation To approach runway 17 of the Ponca City
Municipal Airport in Oklahoma, the pilot must
begin a 3 descent starting from an altitude of
2714 ft. The airport altitude is 1007 ft. How
many miles from the runway is the airplane at the
start of this approach?  
The airplane is 2714 - 1007, or 1707 ft above the
level of the airport. Use trigonometry to find
the desired distance.
The airplane is about 6.2 mi from the runway at
the start of the approach.
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Assignment
Page 484 1-17