Star Prisms & Antiprisms

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(Uniform #79) Octagrammic Antiprism
Vertices:  16  (16[4])
Faces:18  (16 equilateral triangles + 2 regular octagrams)
Edges:32
Symmetry:  8-fold Antiprismatic  (D8v)
Octagram-Triangle Angle:  acos(−sqrt(3*(7−4*sqrt(2)    
    −2*sqrt(2*(10−7*sqrt(2)))))/3)    
≈112.69174466499 degrees
Triangle-Triangle Angle:  acos(−(2*sqrt(2−sqrt(2))−1)/3)    ≈100.189899876 degrees
Dual Solid:  Octagrammic Trapezohedron
(values below based on edge length = 1)
Circumscribed Radius:  sqrt(2*(6−2*sqrt(2)+sqrt(2*(10−7*sqrt(2)))))/4    ≈0.67267324947014347403
Midscribed Radius:  sqrt(2*(4−2*sqrt(2)+sqrt(2*(10−7*sqrt(2)))))/4    ≈0.44998811156820785232
Octagram Center Radius:  sqrt(2*(2*sqrt(2)+sqrt(2*(10−7*sqrt(2)))−2))/4    ≈0.39949478311896564986
Triangle Center Radius:  sqrt(6*(10−6*sqrt(2)    
    +3*sqrt(2*(10−7*sqrt(2)))))/12    
≈0.34518975538012211441


References:[1]Jean Paul Albert Badoureau, Mémoire sur les Figures Isocèles,
Journal de l'École polytechnique 49 (1881), 47-172.