Enneagonal antitegum

The enneagonal antitegum is an antitegum based on the enneagon, constructed as the dual of an enneagonal antiprism. It has 18 kites as faces, with 2 order–9 and 18 order–3 vertices. .

Each face of this polyhedron is a kite with its longer edges $$\frac{2+4\cos\frac\pi9+\csc\frac{\pi}{18}+\sqrt3\csc\frac\pi9}{2} ≈ 8.29086$$ times the length of its shorter edges.