Ball (mathematics)

:A synonym for ball (in geometry or topology, and in any dimension) is disc (or disk); however, a 3-dimensional ball is generally called a ball, and a 2-dimensional ball (e.g., the interior of a circle in the plane) is generally called a disc.

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In mathematics, a ball is the inside of a sphere; both concepts apply not only in 3D but also for lower and higher dimensions, and for metric spaces in general; ball even applies for topological spaces in general.

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