Lesson 8-2 Formulas Circumference Arc Length Area Sector

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.

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

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

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

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°

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