1. Geometry Honors Section 9.1 Segments and Arcs of Circles

2. A *circle is a set of points, in a plane, that are equidistant from a given point. This given point is called the _______ of the circle.
center

3. A circle can be named by using the symbol _____ and naming the center of the circle. The circle to the right is __________.

4. A *radius (plural: radii) is a segment from the center to a point on the circle.

5. A *chord is a segment whose endpoints are on the circle.

6. A *diameter is a chord which contains the center of the circle.

7. An arc is an unbroken part of a circle
An arc is an unbroken part of a circle. Any two distinct points on a circle divide the circle into two arcs. The two points are called the _________of the arc.
endpoints

8. If the two points are the endpoints of a diameter, then each of the two arcs formed is called a __________ A semicircle is named by its two endpoints and another point that lies on the arc. Example: Name two semicircles _____ & _____
semicircle.

9. If the two points are not the endpoints of a diameter, then a minor arc and a major arc are formed.

10. A. minor arc is an arc which is shorter than a semicircle
A *minor arc is an arc which is shorter than a semicircle. A minor arc is named by its two endpoints. Example: Name two minor arcs. _____ & _____

11. A. major arc is an arc which is longer than a semicircle
A *major arc is an arc which is longer than a semicircle. A major arc is named by its two endpoints and another point that lies on the arc. . Example: Name two major arcs. _______ & _______

12. A *central angle of a circle is an angle whose vertex is at the center and whose sides are radii. The arc between the outer endpoints of the two radii is called the __________ arc of the central angle.
intercepted

13. The degree measure of a minor arc is equal to the measure of its central angle. The degree measure of a major arc is equal to 360⁰ - the measure of the associated minor arc. The degree measure of a semicircle is ______.
180⁰

14. When referring to the measure of an arc, use the notation __________

15. 100⁰
38⁰

16. The following theorem mentions congruent circles
The following theorem mentions congruent circles. Two circles are congruent iff their radii are congruent. Chords and Arcs Theorem
In a circle (or in congruent circles), two chords are congruent iff the minor arcs they determine are congruent.

18. Radius and Chord Theorem If a radius is perpendicular to a chord, then the radius bisects the chord and its arc.