Heptagonal-enneagonal duoprism

The heptagonal-enneagonal duoprism or heendip, also known as the 7-9 duoprism, is a uniform duoprism that consists of 7 enneagonal prisms and 9 heptagonal prisms, with two of each joining at each vertex.

Vertex coordinates
The coordinates of a heptagonal-enneagonal duoprism, centered at the origin and with edge length 4sin(π/7)sin(π/9), are given by: where j = 2, 4, 8 and k = 2, 4, 6.
 * $$\left(2\sin\frac\pi9,0,2\sin\frac\pi7,0\right),$$
 * $$\left(2\sin\frac\pi9,0,2\sin\frac\pi7\cos\left(\frac{j\pi}9\right),±2\sin\frac\pi7\sin\left(\frac{j\pi}9\right)\right),$$
 * $$\left(2\sin\frac\pi9,0,-\sin\frac\pi7,±\sqrt3\sin\frac\pi7\right),$$
 * $$\left(2\sin\frac\pi9\cos\left(\frac{k\pi}7\right),±2\sin\frac\pi9\sin\left(\frac{k\pi}7\right),2\sin\frac\pi7,0\right),$$
 * $$\left(2\sin\frac\pi9\cos\left(\frac{k\pi}7\right),±2\sin\frac\pi9\sin\left(\frac{k\pi}7\right),2\sin\frac\pi7\cos\left(\frac{j\pi}9\right),±2\sin\frac\pi7\sin\left(\frac{j\pi}9\right)\right),$$
 * $$\left(2\sin\frac\pi9\cos\left(\frac{k\pi}7\right),±2\sin\frac\pi9\sin\left(\frac{k\pi}7\right),-\sin\frac\pi7,±\sqrt3\sin\frac\pi7\right),$$