Geometry · Circles
Arc Length
HSG-C.B.5
Definition
The distance along an arc, equal to (central angle / 360) times the circumference.
Examples
- A 90 degree arc on a circle covers 90/360, or 1/4, of the circumference.
- A 180 degree arc covers half the circumference.
Key rule
Arc length is the fraction of the circumference cut off by the central angle.
Memory hook
Fraction of the angle times the whole circumference.