Angles Arc Length Sector Area Section 4.1
Objectives I can find co-terminal angles I can convert between radian and degree measures I can calculate arc length and sector area
Co-terminal Angles An angle of xº is co-terminal with angles of xº + k · 360º where k is an integer. An angle of x R is co-terminal with angles of x R + k · 2π R where k is an integer.
Section 4.1: Figure 4.4 Co-terminal Angles
Find 1 positive and 1 negative co-terminal angle
Conversion between Degrees and Radians Using the basic relationship radians = 180º, To convert degrees to radians, multiply degrees by ( radians) / 180 To convert radians to degrees, multiply radians by 180 / ( radians)
Example 1 Convert each angle in degrees to radians 40º 75º -160º
Example cont. Solution: 40º = 40* /180 = 2 /9 75º = 75* /180 = 5 / º = -160* /180 = -8 /9
Convert to degrees 180 degrees 45 degrees 216 degrees 105 degrees
Section 4.1: Figure 4.5, Illustration of Arc Length
Example 1 A circle has a radius of 7 inches. Find the length of the arc intercepted by a central angle of 75°
Example 2 A circle has a radius of 12 meters. Find the length of the arc intercepted by a central angle of π/6 radians
Example 1 A circle has a radius of 7 inches. Find the sector area for a central angle of 75°
Example 2 A circle has a radius of 12 meters. Find the sector area for a central angle of π/6 radians
Homework WS 8-3 Quiz Monday