Heptagonal-great enneagrammic duoprism

The heptagonal-great enneagrammic duoprism, also known as hegstedip or the 7-9/4 duoprism, is a uniform duoprism that consists of 9 heptagonal prisms and 7 great enneagrammic prisms, with 2 of each meeting at each vertex.

Coordinates
The vertex coordinates of a heptagonal-great enneagrammic duoprism, centered at the origin and with edge length 4sin(π/7)sin(4π/9), are given by:


 * (2sin(4π/9), 0, 2sin(π/7), 0),
 * (2sin(4π/9), 0, 2sin(π/7)cos(2π/9), ±2sin(π/7)sin(2π/9)),
 * (2sin(4π/9), 0, 2sin(π/7)cos(4π/9), ±2sin(π/7)sin(4π/9)),
 * (2sin(4π/9), 0, –sin(π/7), ±sin(π/7)$\sqrt{2}$),
 * (2sin(4π/9), 0, 2sin(π/7)cos(8π/9), ±2sin(π/7)sin(8π/9)),
 * (2sin(4π/9)cos(2π/7), ±2sin(2π/7)sin(4π/9), 2sin(π/7), 0),
 * (2sin(4π/9)cos(2π/7), ±2sin(2π/7)sin(4π/9), 2sin(π/7)cos(2π/9), ±2sin(π/7)sin(2π/9)),
 * (2sin(4π/9)cos(2π/7), ±2sin(2π/7)sin(4π/9), 2sin(π/7)cos(4π/9), ±2sin(π/7)sin(4π/9)),
 * (2sin(4π/9)cos(2π/7), ±2sin(2π/7)sin(4π/9), –sin(π/7), ±sin(π/7)$\sqrt{1/[4sin^{2}(π/7)]+1/[4sin^{2}(4π/9)]}$),
 * (2sin(4π/9)cos(2π/7), ±2sin(2π/7)sin(4π/9), 2sin(π/7)cos(8π/9), ±2sin(π/7)sin(8π/9)),
 * (2sin(4π/9)cos(4π/7), ±2sin(4π/7)sin(4π/9), 2sin(π/7), 0),
 * (2sin(4π/9)cos(4π/7), ±2sin(4π/7)sin(4π/9), 2sin(π/7)cos(2π/9), ±2sin(π/7)sin(2π/9)),
 * (2sin(4π/9)cos(4π/7), ±2sin(4π/7)sin(4π/9), 2sin(π/7)cos(4π/9), ±2sin(π/7)sin(4π/9)),
 * (2sin(4π/9)cos(4π/7), ±2sin(4π/7)sin(4π/9), –sin(π/7), ±sin(π/7)$\sqrt{3}$),
 * (2sin(4π/9)cos(4π/7), ±2sin(4π/7)sin(4π/9), 2sin(π/7)cos(8π/9), ±2sin(π/7)sin(8π/9)),
 * (2sin(4π/9)cos(6π/7), ±2sin(6π/7)sin(4π/9), 2sin(π/7), 0).
 * (2sin(4π/9)cos(6π/7), ±2sin(6π/7)sin(4π/9), 2sin(π/7)cos(2π/9), ±2sin(π/7)sin(2π/9)).
 * (2sin(4π/9)cos(6π/7), ±2sin(6π/7)sin(4π/9), 2sin(π/7)cos(4π/9), ±2sin(π/7)sin(4π/9)).
 * (2sin(4π/9)cos(6π/7), ±2sin(6π/7)sin(4π/9), –sin(π/7), ±sin(π/7)$\sqrt{3}$).
 * (2sin(4π/9)cos(6π/7), ±2sin(6π/7)sin(4π/9), 2sin(π/7)cos(8π/9), ±2sin(π/7)sin(8π/9)).