1. Obj: Use angle measures to find arc measures

2. Circle Parts
Central Angle- Angle with the vertex at the center of a circle and endpoints on the circle.
Minor arc- Arc of a circle measuring less than 180⁰
Major arc- Arc of a circle with a measure of 360⁰ - its minor arc
Semicircle- Arc with a measure of 180⁰
Talk about naming arcs. Minor- Endpoints, Major-Endpoints and point on arc

3. Measuring arcs Measure of a circle- 360⁰
Measure of minor angle- the measure of its central angle.
Measure of Major Arc: 360⁰- measure of the minor arc.

4. Find the measure of each arc of the circle, where RT is a diameter.
Is it a minor arc, major arc, or semicircle?

5. Arc Addition
The measure of an arc formed by two adjacent arcs is the sum of the measure of the two arcs.
Part + Part = Whole

6. Arc Addition Example

7. Is the given arc a major arc, minor arc, or semicircle
Is the given arc a major arc, minor arc, or semicircle? Find the measure of the arc.

8. Congruent Circles and Arcs
Congruent Circles- Circles with the same radius
Congruent Arcs- Arcs of congruent circles that have the same measure.

9. Tell whether the red arcs are congruent. Explain why or why not.