1. Chapter 9 Section 3 (Arcs and Central Angles) Central Angle:
Chapter 9 Section 3
(Arcs and Central Angles) B
Central Angle:
(vertex is the center of the circle) C
Minor Arc:
(less than half of a circle) E A F
Major Arc: D
(more than half of a circle)
Semicircle: or
Point A is the center of the circle.
(half of a circle)

2. B If C
Then
And A D
The measure of a semicircle is always 180°.

3. Ex #1: Find the measure of the identified angle of .
Ex #1: Find the measure of the identified angle of T
40° I 1 E A
225°

4. Ex #2: Find the measure of the identified angle of .
Ex #2: Find the measure of the identified angle of D E 1
30° A G

5. Ex #3: Find the measure of the identified angle of .
Ex #3: Find the measure of the identified angle of D B
130° A 1 E C

6. Ex #4: Find the measure of in .
Ex #4: Find the measure of in C
50°
60° B D A E

7. Ex #5: Find the measure of the arcs of .
Ex #5: Find the measure of the arcs of C
88° B
38° 2x
2x – 14 O
3x + 10
78° 3x D 4x A
52°
104° E

8. Chapter 9 Section 3 (Arcs and Central Angles) Homework:
Chapter 9 Section 3
(Arcs and Central Angles)
Homework:
Section 9.3 Classroom Exercises (p. 341)
#1-13 (all)
Section 9.3 Written Exercises
(p. 341–342) #1–11 (all) & 16
9.1 & 9.2 Practice worksheet