Regular polygon common angle is a constructible number—that is, can be written in terms of the four basic arithmetic operations and the extraction of square roots. A "regular skew polygon" in 3-space can be seen as nonplanar paths zig-zagging between two parallel planes, defined as the side-edges of a uniform antiprism. All edges and internal angles are equal. More generally "regular skew polygons" can be defined in "n"-space. Examples include the Petrie polygons, polygonal paths of edges that divide a regular polytope into two halves, and seen as a regular polygon in orthogonal projection. In the infinite limit "regular skew polygons" become
Rectification (geometry) 2r{p,q...}. For polyhedra, a birectification creates a dual polyhedron. Higher degree rectifications can be constructed for higher dimensional polytopes. In general an n-rectification truncates "n-faces" to points. If an n-polytope is (n-1)-rectified, its facets are reduced to points and the polytope becomes its dual. There are different equivalent notations for each degree of rectification. These tables show the names by dimension and the two type of facets for each. Facets are edges, represented as {2}. Facets are regular polygons. Facets are regular or rectified polyhedra. Facets are regular or rectified 4-polytopes. Rectification (geometry) In Euclidean geometry, rectification or complete-truncation is