# 8-5 Angles of Elevation & Depression

8-5 Angles of Elevation & Depression Angles of Elevation Angle of Elevation: The angle between the line of sight and the horizontal when an observer looks upward. of e Lin ht g

i S Angle of Elevation Example 1 Find the angle of elevation of the Sun when a 7.6 meters flagpole casts a 18.2 meter shadow. Round to the nearest tenth of a degree. Tan = Opposite/Adjacent Tan x = 7.6/18.2 x = tan-1 (7.6/18.2) x = 22.7

7.6 m 18.2 m Angle of Depression Angle of Depression: The angle between the line of sight when an observer looks downward and the horizontal. Angle of Depression of e Lin ht g

i S Example 2 A wheelchair ramp is 3 meters long and inclines at 6. Find the height of the ramp to the nearest tenth of a centimeter. Sin = Opposite/Hypotenuse 3m Sin 6 = x/3 6 ? 3(Sin 6) = x

31.4 cm = x Example 3 Two boats are observed by a parasailer 75 meters above a lake. The angles of depression are 12.5 and 7. How far apart are the boats? Tan 7 = 75/x1 x1 (Tan 7) = 75 7 x1 = 75/Tan 7 x1 610.8

75 m 12.5 Tan 12.5 = 75/x2 x2 (Tan 12.5) = 75 12.5 x2 = 75/Tan 12.5 x2 338.3 Answer = x1 x2 = about 273 m 7 Try these