Joined hexacosichoron

The joined hecatonicosachoron, also known as the triangular-bipyramidal chiliadiacosichoron or tibbic, is a convex isochoric polychoron with 1200 triangular bipyramids as cells. It can be obtained as the dual of the rectified hecatonicosachoron.

It can also be obtained as the convex hull of a hecatonicosachoron and a hexacosichoron, where the edges of the hexacosichoron are $$\frac{3(1+\sqrt5)}{4} ≈ 2.42705$$ times the length of those of the hecatonicosachoron.

The ratio between the longest and shortest edges is 1:$$3\sqrt{\frac{9+\sqrt5}{38}}$$ ≈ 1:1.63131. Each face is an isosceles triangle that uses one long and two short edges.

Isogonal derivatives
Substitution by vertices of these following elements will produce these convex isogonal polychora:
 * Triangular bipyramid (1200): Rectified hecatonicosachoron
 * Isosceles triangle (3600): Semi-uniform small rhombated hecatonicosachoron
 * Edge (720): Rectified hexacosichoron
 * Edge (2400): Semi-uniform small disprismatohexacosihecatonicosachoron
 * Vertex (120): Hexacosichoron
 * Vertex (600): Hecatonicosachoron