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Sec. 4.8. Consider two people looking at each other from the top and bottom of a flight of stairs: Angle of Depression Elevation Angle of Elevation –

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Presentation on theme: "Sec. 4.8. Consider two people looking at each other from the top and bottom of a flight of stairs: Angle of Depression Elevation Angle of Elevation –"— Presentation transcript:

1 Sec. 4.8

2 Consider two people looking at each other from the top and bottom of a flight of stairs: Angle of Depression Elevation Angle of Elevation – angle through which the eye moves up from horizontal to look at something above. New Definitions Angle of Depression – angle through which the eye moves down from horizontal to look at something below.

3 The angle of depression of a buoy from the top of a lighthouse 130 feet above the surface of the water is 6. Find the distance x from the base of the lighthouse to the buoy. Guided Practice 6 6 x 130 ft First, draw a diagram:Solve for x algebraically: feet

4 From the top of a 100-ft tall building a man observes a car moving toward the building. If the angle of depression of the car changes from 22 to 46 during the period of observation, how far does the car travel? Guided Practice 22 x 100 ft The diagram: d From the smaller right triangle:

5 From the top of a 100-ft tall building a man observes a car moving toward the building. If the angle of depression of the car changes from 22 to 46 during the period of observation, how far does the car travel? Guided Practice 22 x 100 ft The diagram: d From the larger right triangle: Substitute!!!

6 From the top of a 100-ft tall building a man observes a car moving toward the building. If the angle of depression of the car changes from 22 to 46 during the period of observation, how far does the car travel? Guided Practice 22 x 100 ft The diagram: d feet

7 A large, helium-filled penguin is moored at the beginning of a parade route. Two cables attached to the underside of the penguin make angles of 48 and 40 with the ground and are in the same plane as a perpendicular line from the penguin to the ground. If the cables are attached to the ground 10 feet from each other, how high above the ground is the penguin? Guided Practice x The diagram: 4840 h 10 Definition of the tangent function: Solve both for h: Set equal, solve for x:

8 A large, helium-filled penguin is moored at the beginning of a parade route. Two cables attached to the underside of the penguin make angles of 48 and 40 with the ground and are in the same plane as a perpendicular line from the penguin to the ground. If the cables are attached to the ground 10 feet from each other, how high above the ground is the penguin? Guided Practice x The diagram: 4840 h 10 Plug back in to solve for h!!!

9 A large, helium-filled penguin is moored at the beginning of a parade route. Two cables attached to the underside of the penguin make angles of 48 and 40 with the ground and are in the same plane as a perpendicular line from the penguin to the ground. If the cables are attached to the ground 10 feet from each other, how high above the ground is the penguin? Guided Practice x The diagram: 4840 h 10 feet

10 The top row of the red seats behind home plate at Cincinnati’s Riverfront Stadium is 90ft above the level of the playing field. The angle of depression to the base of the left field wall is 14. How far is the base of the left field wall from a point on level ground directly below the top row? Guided Practice d = distance in question feet

11 The angle of elevation of the top of Proctor’s ego is measured to be at a point 12.3 feet from the base of the ego. How tall is Proctor’s ego? Guided Practice h = height of Proctor’s ego feet

12 While hiking on a level path toward Colorado’s front range, Otis Evans determines that the angle of elevation to the top of Long’s Peak is 30. Moving 1000 ft closer to the mountain, Otis determines the angle of elevation to be 35. How much higher is the top of Long’s Peak than Otis’s elevation? Guided Practice h = height in question feet

13 A U.S. Coast Guard patrol boat leaves Port Cleveland and averages 35 knots (nautical mph) traveling for 2 hours on a course of 53 and then 3 hours on a course of 143. What is the boat’s bearing and distance from Port Cleveland? A B C First, let’s diagram the path of the boat… Now, we need the measure of angle ABC… How about the distances AB and BC? Distance = Speed x Time AB = (35 knots)(2 hours) = 70 naut. mi. BC = (35 knots)(3 hours) = 105 naut. mi

14 A U.S. Coast Guard patrol boat leaves Port Cleveland and averages 35 knots (nautical mph) traveling for 2 hours on a course of 53 and then 3 hours on a course of 143. What is the boat’s bearing and distance from Port Cleveland? A B C Solve the right triangle for AC and : naut. mi.

15 A U.S. Coast Guard patrol boat leaves Port Cleveland and averages 35 knots (nautical mph) traveling for 2 hours on a course of 53 and then 3 hours on a course of 143. What is the boat’s bearing and distance from Port Cleveland? A B C Interpret our answer: The patrol boat is about 126 nautical miles from port, at a bearing of approximately

16 More Practice Problems A boat travels at 40 knots from its home port on a course of 65 for 2 hours and then changes to a course of 155 for 4 hours. Find the distance and bearing from the port to the boat. Port nautical miles Bearing

17 More Practice Problems A ranger spots a fire from a 73-ft tower in Yellowstone National Park. She measures the angle of depression to be. How far is the fire from the tower? 73 ft

18 More Practice Problems A six meter ladder makes an angle of 70 with the ground as it leans against a wall. The ladder then slips slightly so that the angle it makes with the ground changes to 60. How much higher on the wall was the ladder before it slipped? Before slipping: 6 m After slipping: 6 m

19 More Practice Problems A six meter ladder makes an angle of 70 with the ground as it leans against a wall. The ladder then slips slightly so that the angle it makes with the ground changes to 60. How much higher on the wall was the ladder before it slipped? Total change in vertical position on wall: meters


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