Hexacontaèdre trapézoïdal

In geometry, a deltoidal hexecontahedron (also sometimes called a trapezoidal hexecontahedron, a strombic hexecontahedron, or a tetragonal hexacontahedron) is a Catalan solid which is the dual polyhedron of the rhombicosidodecahedron, an Archimedean solid. It is one of six Catalan solids to not have a Hamiltonian path among its vertices. It is topologically identical to the nonconvex rhombic hexecontahedron. The 60 faces are deltoids or kites. The short and long edges of each kite are in the ratio 1:7 + /6 ≈ 1:1.539344663... The angle between two short edges in a single face is arccos(-5-2/20)≈118.2686774705°. The opposite angle, between long edges, is arccos(-5+9/40)≈67.783011547435° . The other two angles of each face, between a short and a long edge each, are both equal to arccos(5-2/10)≈86.97415549104°. The dihedral angle between any pair of adjacent faces is arccos(-19-8/41)≈154.12136312578°. Topologically, the deltoidal hexecontahedron is identical to the nonconvex rhombic hexecontahedron. The deltoidal hexecontahedron can be derived from a dodecahedron (or icosahedron) by pushing the face centers, edge centers and vertices out to different radii from the body center. The radii are chosen so that the resulting shape has planar kite faces each such that vertices go to degree-3 corners, faces to degree-five corners, and edge centers to degree-four points. The 62 vertices of the disdyakis triacontahedron fall in three sets centered on the origin: Twelve vertices are of the form of a unit circumradius regular icosahedron. Twenty vertices are of the form of a scaled regular dodecahedron. Thirty vertices are of the form of a scaled Icosidodecahedron. These hulls are visualized in the figure below: The deltoidal hexecontahedron has 3 symmetry positions located on the 3 types of vertices: The deltoidal hexecontahedron can be constructed from either the regular icosahedron or regular dodecahedron by adding vertices mid-edge, and mid-face, and creating new edges from each edge center to the face centers.