Editing Dual polyhedron (section)

====Canonical duals====
[[File:Dual compound 6-8 max.png|thumb|Canonical [[dual compound]] of cuboctahedron (light) and rhombic dodecahedron (dark). Pairs of edges meet on their common [[midsphere]].]]

Any convex polyhedron can be distorted into a [[Canonical polyhedron|canonical form]], in which a unit [[midsphere]] (or intersphere) exists tangent to every edge, and such that the average position of the points of tangency is the center of the sphere. This form is unique up to congruences.

If we reciprocate such a canonical polyhedron about its midsphere, the dual polyhedron will share the same edge-tangency points, and thus will also be canonical. It is the canonical dual, and the two together form a canonical dual compound.<ref>{{harvtxt|Grünbaum|2007}}, Theorem 3.1, p.&nbsp;449.</ref>