Square-enneagrammic duoprism

The square-enneagrammic duoprism, also known as sastedip or the 4-9/2 duoprism, is a uniform duoprism that consists of 9 cube s and 4 enneagrammic prism s, with 2 of each meeting at each vertex.

The name can also refer to the square-great enneagrammic duoprism, which uses a different stellation of the enneagon.

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


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