1. Lesson 8-2
Formulas
Circumference
Arc Length
Area
Sector

2. Central Angle
A central angle is an angle whose vertex is at the center of the circle.
The arc measure is written as
The measure of a minor arc is the measure of its central angle.
The measure of a major arc is 360 minus the measure of its central angle.

3. CIRCUMFERENCE: Circumference is the distance around the circle.
Formula: Or
where
Example:
Find the circumference of the following circle.
3 cm cm

4. Arc Length Arc length is the distance around an arc. Formula:
The circumference multiplied by the ratio of the center angle and 360°.
Example:
Arc Length 2 cm 72 B C A

5. Area of a Circle
Area of a circle is the number of unit squares that can fit into a circle.
Formula:
Example:
Find the area of the following circle.
3 cm

6. Area of a Sector
Area of a sector is the area of a section of the circle.
Formula:
The area multiplied by the ratio of the center angle and 360°
Example:
Sector
65°

7. Thanks for coming!