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`d = 2*r*sin(a/(2r))`
Enter a value for all fields
The Chord Length from Arc Length and Radius calculator computes the length of a chord (d) on a circle based on the radius (r) of the circle and the length of the arc (a). 
INSTRUCTIONS: Choose units and enter the following:
- (a) Length of Arc
- (r) Radius of Circle
Chord of a Circle (d): The calculator compute the length of the chord in meters. However, this can be automatically converted to other length units via the pull-down menu. The calculator also returns the inner angle (θ) in degrees.
The Math
The formula for the length of a chord is:
where:
- d is the length of the chord
- r is the radius of the circle
- a is the arc length
The length of the chord (d) is the distance between two points on a circle.
- θ= a / r
- sin (θ/2) = ½ d/r
- d = 2•r•sin (θ/2)
- d = 2•r•sin (a/2r)
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