1. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Section 5-3 Circumference and area of a circle 5.3 Circumferences and Areas of Circles

2. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 5.3 Circumferences and Areas of Circles Definitions Circle: A circle is the set of all points in a plane that are the same distance, r, from a given point in the plane known as the center of the circle. The distance r is known as the radius of the circle. The distance d = 2r is known as the diameter of the circle.

3. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 5.3 Circumferences and Areas of Circles Definitions The circumference, C, of a circle with diameter d and radius r is given by: C =  d = 2  r.

4. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 1. Find the circumference of a circle with a radius of 6 inches.

5. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 2. Find the circumference of a circle with diameter of 10 inches.

6. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 5.3 Circumferences and Areas of Circles Definitions The area, A, of a circle with radius r is given by: A =  r 2.

7. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 3. Find the area of a circle with a radius of 3 meters.

8. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 4.Find the approximate area of a circle with a radius of 7 meters.

9. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 5. Find the approximate area of a circle with a diameter of 10 centimeters.

10. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 7. Find the approximate area of #6. 6. Find the shaded area

11. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Definition A sector of a circle is the portion of a circle enclosed by two radii and an arc The area of a sector is given by:

12. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.3 Circumferences and Areas 8. Find the approximate area of the sector of a circle with a diameter of 12 centimeters.

13. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Assignment 5.3 Circumferences and Areas Page 317 # 4-10, 20-29, 31, 33, and 34