Mathcasts Examples Practice More A
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).

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)

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