Octagonal antiprism
# Octagonal antiprism

Uniform octagonal antiprism :

| Type | Prismatic uniform polyhedron |
| - | - |
| Elements | F = 18, E = 32 V = 16 (χ = 2) |
| Faces by sides | 16{3}+2{8} |
| Schläfli symbol | s{2,16} sr{2,8} |
| Wythoff symbol | | 2 2 8 |
| Coxeter diagram | |
| Symmetry group | $D_{8d},$ $[2^+,16],$ (2*8), order 32 |
| Rotation group | $D_8,$ $[8,2]^+,$ (822), order 16 |
| References | $U_{77(f)}$ |
| Dual | Octagonal trapezohedron |
| Properties | convex |
| Vertex figure 3.3.3.8 ||

In geometry, the octagonal antiprism is the 6th in an infinite set of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps.

Antiprisms are similar to prisms except the bases are twisted relative to each other, and that the side faces are triangles, rather than quadrilaterals.

In the case of a regular 8-sided base, one usually considers the case where its copy is twisted by an angle 180°/n. Extra regularity is obtained by the line connecting the base centers being perpendicular to the base planes, making it a right antiprism. As faces, it has the two n-gonal bases and, connecting those bases, 2n isosceles triangles.

If faces are all regular, it is a semiregular polyhedron.

