1. Angles of Elevation and Depression
Section 4.8

2. angle of elevation – an angle formed by a horizontal line and the line of sight to an object above the level of the horizontal.
angle of elevation

3. angle of depression – an angle formed by a horizontal line and the line of sight to an object below the level of the horizontal.
angle of depression

4. Example
The angle of depression of a buoy from the top of the Barnegat Bay lighthouse 130 feet above the surface of the water is 6º. Find the distance from the base of the lighthouse to the buoy.

5. From the top of the 100 ft tall Altgelt Hall a man observes a car moving toward the building. If the angle of depression of the car changes from 22º to 46º during the period of observation, how far does the car travel?

6. A large helium filled penguin is moored at the beginning of a parade route awaiting the start of the parade. Two cables attached to the underside of the penguin make angles of 48º and 40º with the ground and are in the same plane as a perpendicular line from the ground. (See page 426) If the cables are attached to the ground 10 feet from each other, how high above the ground is the penguin?

7. Try This A girl spots a tree with an angle of elevation of 25°
to the top of
the tree and an angle of depression of 15° to the bottom of the tree from eye level. Her eye level is 165 cm. How far is the girl from the tree? How high is the tree?

8. Try This 25° 165 cm 15° Distance to tree: 615.8 cm
Height of tree: cm

9. Extra Practice
Page 431: 1, 3, 5
The angle of elevation of the top of the Ulm Cathedral from a point 300 ft away from the base of its steeple on level ground is 60º.
Find the height of the cathedral.

10. 3. The angle of depression from the top of the Smoketown Lighthouse 120 ft above the surface of the water to a buoy is 10º. How far is the buoy from the lighthouse?

11. 5. A guy wire connects the top of an antenna to a point on level ground 5 ft from the base of the antenna. The angle of elevation formed by this wire is 80º. What are the lengths of the wire and the height of the antenna?