1. A line intersecting a circle - Draw the possibilities 1 2 0 5.7 Getting Started

2. A circle intersecting a circle - Draw the possibilities 0 1 2 ∞ 5.7 Getting Started

3. Central angle: angle that has vertex at center of circle A o B <AOB is a central angle 5.8 Arcs and Central Angles

4. Arc: part of the circumference *many times, I use 3 letters for an arc, just to be sure people know which one I’m talking about Like AXB A * Or sometimes we use minor and major arc o X B AB  usually identifies the smaller red arc 5.8 Arcs and Central Angles

5. Measure of an arc: measure of the central angle that eats it *this is different than the distance of an arc! A o 120o X B mAB is 120o mAXB is 240o 5.8 Arcs and Central Angles

6. Chord: segment that connects 2 points on a circle A B o F E C D AC, BF, and DE are chords 5.8 Arcs and Central Angles

7. Theorem 2 chords are congruent iff their corresponding arcs are congruent. A o C 70o 70o B D If AB CD, then AB CD 5.8 Arcs and Central Angles