1. Find Arc measures
10.2

2. Vocab
Central Angle: an angle where the vertex is at the center of the circle.

3. And the vocab continues
Minor arc: an angle inside a circle whose measure is less than 180°. (They only need 2 letters to be named but can also have 3 letters.)
Major arc: an angle inside a circle whose measure is greater than 180° or the arc that is not the minor arc. (They require 3 letters to be named)
Semicircle:
Half a circle

4. Name the minor and major arc
I’m a minor!
I’m a major!

5. Arc Addition postulate
This theorem allows us to add arcs

6. Find the indicated arc

7. Find the indicated arc
360 – 90 = 270º

8. Find the indicated arc
360 ÷3 = 120º

9. Finding measures of arcs, where EB is a diameter
75º
= 145º
75o
= 110º
35o
360 – 110 = 250º

10. Word Problems
306o A c B D
306
360 – 306 = 54º
= 234º
54º
180º

11. Congruency
Circles are said to be congruent if and only if their radii are the same.
Arcs are considered to be congruent if they are the same measure and the circles they are contained in are also congruent.
2 arcs of the same measure in the same circle are considered congruent.

12. Congruent?

13. Congruent?

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