Download Chapter 9 Lesson 3

Chapter 9 Lesson 3
Objective: To use angles of
elevation and depression to
solve problems.
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.
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.
Example 1:
Identifying Angles of Elevation and Depression
Describe each angle as it relates to the situation shown:
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.
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.
Assignment
Page 484
#1-17