Parts of a circle – Arcs

sector circleParts of a circle:

Sector: An area inside the circle bounded by 2 radii and an arc.

A portion of the circle (area)

Arc: A curved segment of the circle.

A portion of the circle (perimeter)

Sector Area = (portion of circle)(area of entire circle)

Arc Length = (portion of circle)(circumference of entire circle)

Example: radius MOL =10 units central angle MOL = 80°

area of circle O = 100 π

circumference of circle O = 20  π

“portion of the circle”:   80°/360° = 2/9

therefore, sector area = 2/9 · 100 π  = 69.8 sq. units (approximately)

arc length = 20  π = 13.96 units (approximately)

arcs circle

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