Star Dipyramids & Trapezohedra

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Octagrammic Concave Trapezohedron
Vertices:  18  (16[3] + 2[8])
Faces:16  (tri-equiangular darts)
Edges:32  (16 short + 16 long)
Symmetry:  8-fold Antiprismatic  (D8v)
Dihedral Angle:  acos((5+6*sqrt(2)+2*sqrt(130−79*sqrt(2)))/47)    ≈62.040763987 degrees
Dual Solid:  Octagrammic Crossed Antiprism
(values below based on unit-edge-length Octagrammic Crossed Antiprism)
Short Edge (16):  sqrt(2*(8−5*sqrt(2)+sqrt(2*(58−41*sqrt(2)))))/2    ≈0.74653912492614494202
Long Edge (16):  sqrt(1+sqrt(2)+sqrt(2+sqrt(2)))    ≈2.0644545592954252673
[8]-Vertex Radius (2):  sqrt(2*(30−20*sqrt(2)    
    −sqrt(2*(850−601*sqrt(2)))))/4    
≈0.41475491559346828094
[3]-Vertex Radius (16):  sqrt(6*(2+sqrt(2*(2−sqrt(2)))))/4    ≈1.0751265391151163181
Edge-scribed Radius:  sqrt(2*(4−2*sqrt(2)−sqrt(2*(10−7*sqrt(2)))))/4    ≈0.30067244346752264027
Inscribed Radius:  sqrt(94*(146−88*sqrt(2)    
    −5*sqrt(2*(706−497*sqrt(2)))))/188    
≈0.15494942848575199700