Central angles and arcs are related in a circle. A central angle has its vertex at the circle's center and subtends an arc. The measure of an arc is the fraction of 360 degrees it occupies, while the length is the distance along the circle. A minor arc has a measure less than 180 degrees, while a major arc's measure is greater than 180 degrees. Concentric circles share the same center.

1. Unit 10 Day 2 Objective: Explore the relationships between arcs and central angles in a circle.

2. Daily Quiz When finished, get out your Circles tool kit.

3. Vocabulary Central Angle: Has a vertex at the center of the circle. Arc: Part of the circle O A B C

4. Vocabulary Arc Length vs. Arc Measure Arc Measure is measured in degrees and is a fraction of the 360° of a circle. Arc Length is how far it is from one point to another as we travel along the circle O A B C

5. Vocabulary Minor Arc: Arc measure that is < 180° ( ) Major Arc: Arc measure that is > 180° ( ) O A B C

6. Vocabulary Concentric Circles: Circles that share the same center.

7. Classwork CS 11 - 15

8. Closure Find the measure of major arc if arc ED = 98°?