1. Splash Screen

2. Vocabulary circle center radius chord diameter concentric circles circumference pi (  ) inscribed circumscribed

3. Concept

4. Example 1 Identify Segments in a Circle A. Name the circle and identify a radius.

5. Example 1 Identify Segments in a Circle B. Identify a chord and a diameter of the circle.

6. Example 1 A. Name the circle and identify a radius. A. B. C. D.

7. Example 1 B. Which segment is not a chord? A. B. C. D.

8. Concept

9. Example 2 Find Radius and Diameter Answer: QV = 10.5 cm d= 2rDiameter Formula 21= 2rd = 21 10.5= rSimplify. If RT = 21 cm, what is the length of QV? RT is a diameter and QV is a radius.

10. Example 2 A.12 cm B.13 cm C.16 cm D.26 cm If QS = 26 cm, what is the length of RV?

11. Concept

12. Example 3 Find Measures in Intersecting Circles

13. Example 3 Find Measures in Intersecting Circles First, find ZY. WZ + ZY= WY 5 + ZY= 8 ZY= 3 Next, find XY. XZ + ZY= XY 11 + 3= XY 14= XY Since the diameter of is 16 units, WY = 8. Similarly, the diameter of is 22 units, so XZ = 11. WZ is part of radius XZ and part of radius WY.

14. Example 3 Find Measures in Intersecting Circles Answer: XY = 14 units

15. Example 3 A.3 in. B.5 in. C.7 in. D.9 in.

16. Concept

17. Example 4 Find Circumference CROP CIRCLES A series of crop circles was discovered in Alberta, Canada, on September 4, 1999. The largest of the three circles had a radius of 30 feet. Find its circumference. Since the radius is 30 feet, and d = 2r, the diameter = 2(30) or 60 feet. C=  dCircumference formula =  (60)Substitution = 60  Simplify. ≈ 188.50Use a calculator. Answer: The circumference of the crop circle is 60  feet or about 188.50 feet.

18. Example 4 A.377.0 feet B.392.5 feet C.408.3 feet D.422.1 feet The Unisphere is a giant steel globe that sits in Flushing Meadows-Corona Park in Queens, New York. It has a diameter of 120 feet. Find its circumference.

19. Example 5 Find Diameter and Radius Find the diameter and the radius of a circle to the nearest hundredth if the circumference of the circle is 65.4 feet. Circumference Formula Substitution Use a calculator. Divide each side by.

20. Example 5 Find Diameter and Radius Answer:d ≈ 20.82 ft; r ≈ 10.41 ft Radius Formula Use a calculator.

21. Example 5 A.8.4 m B.5.35 m C.2.67 m D.16.8 m Find the radius of a circle to the nearest hundredth if its circumference is 16.8 meters.

22. Assignment: pg 701-702 #10-38 EVENS only ----Then ask about making corrections to last time’s worksheet!