Arc Length and Area of Sector

The length of part of the circumference.

Arc Length

The length of the arc depends on what two things?

1) The measure of the arc.2) The size of the circle.

An arc length measures distance while the measure of an arc is in degrees.

A region bounded by 2 radii and an arc.

Sector of a circle

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Portions of a Circle: Determine the Arc measure based on the portion given.

A. B. C. D.

¼ of a circle: ½ of a circle: 1/3 of circumference : 6π out of a total 36π on the circle: ¼ ● 360

90o

90o

½ ● 360

180o

180o

1/3 ● 360

120o

120o

1/6 ● 360

60o

60o

Area of a Sector Formula

m360πr2Area of a sector =

measure of the central angle or arc

The fraction of the circle!

The area of the entire circle!

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Arc Length Formula

m3602πrArc Length =

measure of the central angle or arc

The fraction of the circle!

The circumference of the entire circle!

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