In geometry, the **triangular orthobicupola** is one of the Johnson solids (*J*_{27}). As the name suggests, it can be constructed by attaching two triangular cupolas (*J*_{3}) along their bases. It has an equal number of squares and triangles at each vertex; however, it is not vertex-transitive. It is also called an *anticuboctahedron*.

The *triangular orthobicupola* is the first in an infinite set of orthobicupolae.

The *triangular orthobicupola* has a superficial resemblance to the cuboctahedron, which would be known as the *triangular gyrobicupola* in the nomenclature of Johnson solids — the difference is that the two triangular cupolas which make up the triangular orthobicupola are joined so that pairs of matching sides abut (hence, "ortho"); the cuboctahedron is joined so that triangles abut squares and vice versa. Given a triangular orthobicupola, a 60-degree rotation of one cupola before the joining yields a cuboctahedron. Hence, another name for the triangular orthobicupola is the *anticuboctahedron*.

The elongated triangular orthobicupola (*J*_{35}), which is constructed by elongating this solid, has a (different) special relationship with the rhombicuboctahedron.

The 92 Johnson solids were named and described by Norman Johnson in 1966.

The dual of the *triangular orthobicupola* is called a *trapezoid-rhombic dodecahedron*. It has 6 rhombic and 6 trapezoidal faces. It is similar to the rhombic dodecahedron and both of them are space-filling polyhedra.

Read more about Triangular Orthobicupola: Formulae