1. 10-1Circles and Circumference You identified and used parts of parallelograms. Identify and use parts of a circle. Solve problems involving the circumference of a circle.

2. Definition A circle is the locus of points in a plane equidistant from a given point. That point is the center of the circle. center

3. Circle Parts A circle is named by its center. A radius is a segment from the center to any point on the circle. A diameter is a segment that contains the center of the circle and has endpoints on the circle. סּQסּQ סּQ radius diameter

4. Definition A chord is a line segment that joins two points on a circle. AB is a chord of סּD Where would you find the largest chord in any circle? A B D

5. p. 697

6. A. Name the circle and identify a radius.

7. B. Identify a chord and a diameter of the circle.

8. A. Name the circle and identify a radius. A. B. C. D.

9. B. Which segment is not a chord? A. B. C. D.

10. By definition, the distance from the center of a circle to any point on the circle is always the same. All radii of a circle are congruent. A diameter (d) is made is made up of two radii. 1 raduis p. 698

11. 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.

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

13. Exterior, Interior, Concentric interior exterior Concentric circles are two coplanar circles with the same center.

14. p. 698

15. 5

16. A.3 in. B.5 in. C.7 in. D.9 in.

17. 10-1 Assignment Day 1 p. 701, 10-21