Hexagonal-great enneagrammic duoprism

The hexagonal-great enneagrammic duoprism, also known as the 6-9/4 duoprism, is a uniform duoprism that consists of 9 hexagonal prisms and 6 great enneagrammic prisms, with 2 of each meeting at each vertex.

Coordinates
The vertex coordinates of a hexagonal-great enneagrammic duoprism, centered at the origin and with edge length 2sin(4π/9), are given by:


 * (±2sin(4π/9), 0, 1, 0),
 * (±2sin(4π/9), 0, cos(2π/9), ±sin(2π/9)),
 * (±2sin(4π/9), 0, cos(4π/9), ±sin(4π/9)),
 * (±2sin(4π/9), 0, –1/2, ±$\sqrt{3}$/2),
 * (±2sin(4π/9), 0, cos(8π/9), ±sin(8π/9)),
 * (±sin(4π/9), ±sin(4π/9)$\sqrt{2}$, 1, 0),
 * (±sin(4π/9), ±sin(4π/9)$\sqrt{1+1/[4sin^{2}(4π/9)]}$, cos(2π/9), ±sin(2π/9)),
 * (±sin(4π/9), ±sin(4π/9)$\sqrt{3}$, cos(4π/9), ±sin(4π/9)),
 * (±sin(4π/9), ±sin(4π/9)$\sqrt{3}$, –1/2, ±$\sqrt{3}$/2),
 * (±sin(4π/9), ±sin(4π/9)$\sqrt{3}$, cos(8π/9), ±sin(8π/9)).