2. You will find the central angle, the arc and the arc length of a circle.

3. Lets’ look at some vocabulary. Central angle is an angle whose vertex is the center of the circle. Central angle

4. Lets’ find the central angle that is 31% of the circle. 31% of 360 0.31  360 0 111.6 0

5. Here comes some more terms. Semicircle is half of a circle. 180 0 semicircle T R S P TRS = 180 0 ) mTRS = m  TPS )

6. Here comes some more terms. A minor arc is smaller than a semicircle. ( less than 180 0 ) RS < 180 0 ) mRS = m  RPS ) Minor arc T R S P

7. Here comes some more terms. A major arc is greater than a semicircle. ( bigger than 180 0 ) RTS > 180 0 ) Major arc T R S P mRTS = 360 0 - mRS ) )

8. Here are a few more terms Circumference of a Circle is the distance around the out side of the circle. C = 2  r or C =  d

9. Here are a few more terms Arc Length is the measure of the out side of a central angle. Minor arc T R S P Arc length =  2  r mRS / 360 0 (

10. Hold on, lets’ work a problem. Find the measure of each arc TC 128 0 T C D P B ( = 128 CD ( = 52 ( TCD = 180 ( BDC = 142

11. Now lets’ find the length of the arc. Arc length =  2  r mRS / 360 0 ( 45 0 R 14 cm S Arc length =  2  (14) 45 / 360 Arc length = 7/27/2

13. Assignment Workbook Page 449 all