1. 3 Radian Measure and Circular Functions © 2008 Pearson Addison-Wesley. All rights reserved

2. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-2 3.1 Radian Measure 3.2 Applications of Radian Measure Radian Measure and Circular Functions 3

3. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-3 Radian Measure 3.1 Radian Measure ▪ Converting Between Degrees and Radians ▪ Finding Function Values for Angles in Radians

4. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-4 Convert each degree measure to radians. 3.1 Example 1 Converting Degrees to Radians (page 103)

5. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-5 Convert each radian measure to degrees. 3.1 Example 2 Converting Radians to Degrees (page 103)

6. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-6 Find each function value. 3.1 Example 3 Finding Function Values of Angles in Radian Measure (page 105)

7. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-7 Applications of Radian Measure 3.2 Arc Length on a Circle ▪ Area of a Sector of a Circle

8. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-8 A circle has radius 25.60 cm. Find the length of the arc intercepted by a central angle having each of the following measures. 3.2 Example 1 Finding Arc Length Using s = rθ (page 109) Convert θ to radians.

9. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-9 Erie, Pennsylvania is approximately due north of Columbia, South Carolina. The latitude of Erie is 42° N, while that of Columbia is 34° N. Find the north-south distance between the two cities. 3.2 Example 2 Using Latitudes to Find the Distance Between Two Cities (page 110) The radius of the earth is about 6400 km. The central angle between Erie and Columbia is 42° – 34° = 8°. Convert 8° to radians:

10. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-10 Use s = rθ to find the north-south distance between the two cities. 3.2 Example 2 Using Latitudes to Find the Distance Between Two Cities (cont.) The north-south distance between Erie and Columbia is about 890 km.

11. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-11 A rope is being wound around a drum with radius.327 m. How much rope will be wound around the drum if the drum is rotated through an angle of 132.6°? 3.2 Example 3 Finding a Length Using s = rθ (page 110) The length of rope wound around the drum is the arc length for a circle of radius.327 m and a central angle of 132.6°.

12. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-12 Use s = rθ to find the arc length, which is the length of the rope. 3.2 Example 3 Finding a Length Using s = rθ (cont.) The length of the rope wound around the drum is about.757 m. Convert 132.6° to radians:

13. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-13 Two gears are adjusted so that the smaller gear drives the larger one. If the radii of the gears are 3.6 in. and 5.4 in., and the smaller gear rotates through 150°, through how many degrees will the larger gear rotate? 3.2 Example 4 Finding an Angle Measure Using s = rθ (page 111) First find the radian measure of the angle, and then find the arc length on the smaller gear that determines the motion of the larger gear.

14. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-14 The arc length on the smaller gear is 3.2 Example 4 Finding an Angle Measure Using s = rθ (cont.) An arc with length 3π cm on the larger gear corresponds to an angle measure θ radians, where The larger gear will rotate through 100°.

15. Copyright © 2008 Pearson Addison-Wesley. All rights reserved. 3-15 Find the area of a sector of a circle having radius 15.20 ft and central angle 108.0°. 3.2 Example 5 Finding the Area of a Sector (page 112) The area of the sector is about 217.8 sq ft.