1. Section 7-7: Circles: Area of circles, sectors, and segments April 10, 2012

2. Warm-up: (20 mins)  Create your own figure using a circle and at least 2 other types of shapes. Include at least 5 shapes.  Swap with your partner.  Find the perimeter/circumference of the figure.  Check each other’s work.

3. Questions on Homework?

4. Section 7-7 C ircles: Area of circles, sectors, and segments  Objective: Today you will learn to find areas of circles sectors segments

5. Area of a Circle  Area of a parallelogram = b*h = ½ C*r  C = 2πr Area of a circle = ½ (2πr)*r = πr 2  Area of our cookie cake is ____________.

6. Example 1: Find the exact area of these circles 1.2. 3. d = 16 ft4. r = 5.3 cm Example 2: What is the radius of a circle with area = 144 π m 2 ?

7. Area of a Sector: How big is your piece of the pie?  Sector – region bounded by two radii and their intercepted arc  Area of sector = * area of circle

8. Example 3: Find the area of shaded sector

9. Example 4: Find area of sectors with the given information: a) mXY = 72 0 ; r = 20cm b) mMN = 120 0 ; r = 6 ft c) mAB = 150 0 ; d = 8 in

10. Example 5: Find areas in terms of π Circle A = Sector CD = Sector DEC = Sector CDE = Sector ED = Sector CD + Sector DEC =

11. Segment of a circle Segment of a circle – region of a circle bounded by an arc and the segment joining its endpoints

12. Area of a Segment of a circle Area of sector - Area of triangle = Area of segment

13. Example 6: Find area of shaded segment. Round your answer to the nearest tenth.

14. Example 7: Find area of shaded segment. Round your answer to the nearest tenth.

15. Example 7 (cont’d): Find area of shaded segment. Round your answer to the nearest tenth.

17. Example 8: Find area of shaded segment. Round your answer to the nearest tenth.

18. Example 9: Find area of shaded segment. Round your answer to the nearest tenth.

19. Example 10: Find area of shaded segments. Round your answer to the nearest hundredth. Given: AD = 8√3 m ∠ AEF = 60 0

20. Wrap-up  Today you learned to find areas of circles sectors segments  Tomorrow you will learn about Geometric Probability Homework (H)  p. 397 # 1 - 11, 17 – 19, 22, 23, 25, 27, 32, 35 Homework (R)  p. 397 # 1 - 11, 17 – 19, 22, 25, 26, 27, 28, 35