Hitting Set
Let 
be a collection of subsets of a finite set 
. The smallest subset 
of that meets every member of is called the hitting set or Vertex Cover. Finding the hitting set is an NP-Complete Problem.
- Trisectrix
- Trisectrix of Catalan
- Trisectrix of Maclaurin
- Triskaidecagon
- Triskaidekaphobia
- Tritangent
- Tritangent Triangle
- Trivial
- Trivialization
- Trochoid
- Tromino
- True
- Truncate
- Truncated Cone
- Truncated Cube
- Truncated Cuboctahedron
- Truncated Dodecadodecahedron
- Truncated Dodecahedron
- Truncated Great Dodecahedron
- Truncated Great Icosahedron
- Truncated Hexahedron
- Truncated Icosahedron
- Truncated Icosidodecahedron
- Truncated Octahedral Number
- Truncated Octahedron