Arc Length - Circle

Definition: Arc length is the length of the piece of circle with radius r cut by central angle α.

Interactivity: Arc Length - Circle Directions for Interactivity

Directions: In the interactivity, click and drag the sliders for radius and angle α.

Notice that the arc length is always the radius multiplied by the angle α (measured in radians).

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Regulations:

To convert from degrees to radians, multiply by: π/180° (the degree symbols will cancel)
To convert from radians to degrees, multiply by: 180°/π (the degree symbol remains)