Geometry & Trigonometry
Basic

Arc Length

Length of a circular arc (θ in radians).

Formula

s=rθs = r\theta

Variables

rRadius
\thetaAngle in radians

Example

Radius 10, angle 1.5 rad: s = 10·1.5 = 15 units.

Did You Know?

Arc length is why radians are natural: in radians, arc length is simply radius times angle.

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