|Bowers style acronym||Het|
|Coxeter diagram||m2m7o ()|
|Faces||14 isosceles triangles|
|Vertex figure||2 heptagons, 7 squares|
|Measures (edge length 1)|
|Conjugates||Heptagrammic tegum, Great heptagrammic tegum|
|Abstract & topological properties|
|Symmetry||I2(7)×A1, order 28|
The heptagonal tegum or het, also called a heptagonal bipyramid, is a tegum with a heptagon as the midsection, constructed as the dual of a heptagonal prism. It has 14 isosceles triangles as faces, with 2 order–7 and 7 order–4 vertices.
In the variant obtained as the dual of a uniform heptagonal prism, the side edges are times the length of the edges of the base heptagon. Each face has apex angle and base angles . If the base heptagon has edge length 1, its height is .