1. Bellringer W 3-23-11 Convert 210° to radians Convert to degrees

2. Review Section 5.1 Homework Pg. 245 (24-27, 32-34, 40-42, 48, 52-54) 24. III25. III26. II27. III 32. 33. 34. 40. 60°41. -200°42. 240° 48. -60° -> 300° and -420° 52. 30°53.54. 50°

3. Writing assignment Pretend you are an angle… – Write at least 2 paragraphs explaining what you look like to someone who wants to know your details. Are you positive or negative? Are you quadrantal? Or which quadrant are you in? How many degrees and radians are you? – USE CORRECT MATHEMATICAL TERMS ! ! ! (Use your sheet with new terms on it.)

4. Section 5.2 Central Angle – angle of a circle whose vertex lies at the center of the circle

5. Arclength Arclength = s = rθ(in radians) Ex: Find the length of an arc with a central angle of 42° in a circle with r = 8 cm. – s = rθ – Must convert to radians: 42°( ) = – s = (8)( ) ≈ 5.86 cm

6. Arclength (2) Practice: 1. Find the length of an arc with a central angle of 60° in a circle with r = 10 cm. 2. Find the length of an arc with a central angle of 210° in a circle with r = 12 cm.

7. Linear and Angular Velocity Linear velocity ->, whereis our angular velocity.

8. Linear and Angular Velocity (2) Ex: (#3, pg. 249) A pulley of radius 12cm turns at 7 revolutions per second. What is the linear velocity of the belt driving the pulley in meters per second.

9. Answer to Ex. = 12( ) = 168 ≈ 527.788 cm/sec. ≈ 5.278 m/sec. Another example: #4, pg 249

10. Area of a Circular Sector (Looks familiar to area of a circle…)

11. Area of a Circular Sector (2) Ex: Find the area of a circular sector with a central angle of and a radius of 7 cm. A = ( )(7 2 )( ) A ≈ 57.73 cm.

12. Area of a Circular Sector (3) Practice: 1.Find the area of the circular sector with a radius of 16 cm and a central angle of.95 radians. 2.Find the area of the circular sector with a radius of 5 cm and a central angle of 42°.

13. Homework Section 5.2 Pg. 251 (17, 21, 24, 28, 29)