Diameter (original) (raw)
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The diameter of a circle is the distance from a point on the circle to a point 
radians away, and is the maximum distance from one point on a circle to another. The diameter of a sphere is the maximum distance between two antipodal points on the surface of the sphere.
If 
is the radius of a circle or sphere, then
. The ratio of the circumference 
of a circle or great circle of a sphere to the diameter 
is pi,
See also
Brocard Diameter, Circumference, Circumradius, Circumsphere,Generalized Diameter, Graph Diameter, Pi, Polygon Diameter, Radius, Sphere,Transfinite Diameter Explore this topic in the MathWorld classroom
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Cite this as:
Weisstein, Eric W. "Diameter." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Diameter.html