Disk
An 
-D disk (or Disc) of Radius 
is the collection of points of distance 
(Closed Disk)or 
(Open Disk) from a fixed point in Euclidean -space. A disk is theShadow of a Ball on a Plane Perpendicular to the Ball-Radiant Point line.
The -disk for 
is called a Ball, and the boundary of the -disk is a 
-Hypersphere. Thestandard -disk, denoted 
(or 
), has its center at the Origin and has Radius
.
- Tetrad
- Tetradecagon
- Tetradecahedron
- Tetradic
- Tetradyakis Hexahedron
- Tetraflexagon
- Tetragon
- Tetrahedral Coordinates
- Tetrahedral Graph
- Tetrahedral Group
- Tetrahedral Number
- Tetrahedral Surface
- Tetrahedroid
- Tetrahedron
- Tetrahedron 10-Compound
- Tetrahedron 5-Compound
- Tetrahedron Inscribing
- Tetrahemihexacron
- Tetrahemihexahedron
- Tetrakaidecagon
- Tetrakaidecahedron
- Tetrakis Hexahedron
- Tetranacci Number
- Tetrix
- Tetromino