In geometry, polyhedra are associated into pairs called duals, where the vertices of one correspond to the faces of the other
The dual of the dual is the original polyhedron
The dual of a polyhedron with equivalent vertices is one with equivalent faces, and of one with equivalent edges is another with equivalent edges
Cube and its dual Octahedron 正方體與其對偶正八面體
Dodecahedron and its dual Icosahedron 正十二面體與其對偶正二十面體
Tetrahedron and its dual Tetrahedron 正四面體為本身對偶