1. PIB Geometry 11-5: Circumference and Area of Circles

2. 11-5 Warm Up To the nearest hundredth, find the area of a regular 20-gon inscribed in a circle of radius 1.

3. Turn in 11-4

4. 11-5 Objectives Know and use the formulas for the circumferences and areas of circles.

5. Formulas so far…

6. But first, let’s talk pi for a second

7. Here’s a cool demo: Calculating Pi\package.bluej

8. 11-5 Formulas

9. Examples A circle has a diameter of 10 cm. Find its circumference and its area.

10. Examples

11. Mr. Cawelti can ride his bike fast. Like really fast. How fast you ask? 20 rotations per second fast. If the area of the region enclosed in his tires is 5 ft 2, how far will he travel in a 60 second ride?

12. Examples Find the area of the shaded region.

13. 11-5 Homework p. 448: #1-23 odd, 27, 29, 26 Becky Hoyt’s gift to you: https://www.youtube.com/watch?v=-z4SUypJZxo