Catalan Solids

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Triakis Octahedron
Vertices:  14  (8[3] + 6[8])
Faces:24  (isosceles triangles)
Edges:36  (24 short + 12 long)
Symmetry:  Full Octahedral  (Oh)
Dihedral Angle:  acos(−(3+8*sqrt(2))/17)    ≈147.350100126 degrees
Dual Solid:  Truncated Cube
(values below based on unit-edge-length Truncated Cube)
Short Edge (24):  2
Long Edge (12):  2+sqrt(2)    ≈3.4142135623730950488
[3]-Vertex Radius (8):  sqrt(3)    ≈1.73205080756887729353
[8]-Vertex Radius (6):  1+sqrt(2)    ≈2.4142135623730950488
Edge-scribed Radius:  1+sqrt(2)/2    ≈1.7071067811865475244
Inscribed Radius:  sqrt(17*(23+16*sqrt(2)))/17    ≈1.6382813268065143234
Volume:4*(3+2*sqrt(2))    ≈23.313708498984760390


References:[1]Eugène Catalan, Mémoire sur la Théorie des Polyèdres,
Journal de l'École polytechnique 41 (1865), 1-71, +7 plates.