2. CHAPTER 8 Geometry Slide 2Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. 8.1Basic Geometric Figures 8.2Perimeter 8.3Area 8.4Circles 8.5Volume and Surface Area 8.6Relationships Between Angle Measures 8.7Congruent Triangles and Properties of Parallelograms 8.8Similar Triangles

3. OBJECTIVES 8.4 Circles Slide 3Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. aFind the length of a radius of a circle given the length of a diameter, and find the length of a diameter given the length of a radius. bFind the circumference of a circle given the length of a diameter or a radius. cFind the area of a circle given the length of a diameter or a radius. dSolve applied problems involving circles.

4. 8.4 Circles a Find the length of a radius of a circle given the length of a diameter, and find the length of a diameter given the length of a radius. Slide 4Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. A diameter is a segment that passes through the center of the circle and has endpoints on the circle. A radius is a segment with one endpoint on the center and the other endpoint on the circle.

5. 8.4 Circles DIAMETER AND RADIUS Slide 5Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. Suppose that d is the length of the diameter of a circle and r is the length of the radius. Then

6. EXAMPLE 8.4 Circles a Find the length of a radius of a circle given the length of a diameter, and find the length of a diameter given the length of a radius. 1 Slide 6Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. Find the length of a radius of this circle. The radius is 6 m.

7. 8.4 Circles b Find the circumference of a circle given the length of a diameter or a radius. Slide 7Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. The circumference of a circle is the distance around it. Calculating circumference is similar to finding the perimeter of a polygon.

8. 8.4 Circles CIRCUMFERENCE AND DIAMETER Slide 8Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

9. EXAMPLE 8.4 Circles b Find the circumference of a circle given the length of a diameter or a radius. 3 Slide 9Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

10. 8.4 Circles CIRCUMFERENCE AND RADIUS Slide 10Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. The circumference C of a circle of radius r is given by

11. EXAMPLE 8.4 Circles b Find the circumference of a circle given the length of a diameter or a radius. 4 Slide 11Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

12. 8.4 Circles AREA OF A CIRCLE Slide 12Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

13. EXAMPLE 8.4 Circles c Find the area of a circle given the length of a diameter or a radius. 7 Slide 13Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

14. EXAMPLE 8.4 Circles d Solve applied problems involving circles. 8Area of Pizza Pans Slide 14Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. How much larger is a pizza made in a 16-in.-square pizza pan than a pizza made in a 16-in.-diameter circular pan?

15. EXAMPLE 8.4 Circles d Solve applied problems involving circles. 8Area of Pizza Pans Slide 15Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc. First, we make a drawing of each.

16. EXAMPLE 8.4 Circles d Solve applied problems involving circles. 8Area of Pizza Pans Slide 16Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.

17. EXAMPLE 8.4 Circles d Solve applied problems involving circles. 8Area of Pizza Pans Slide 17Copyright 2012, 2008, 2004, 2000 Pearson Education, Inc.