Platonic Solids

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(Uniform #22) Icosahedron
Vertices:  12  (12[5])
Faces:20  (equilateral triangles)
Edges:30
Symmetry:  Full Icosahedral  (Ih)
Dihedral Angle:  acos(−sqrt(5)/3)    ≈138.189685104 degrees
Dual Solid:  Dodecahedron
(values below based on edge length = 1)
Circumscribed Radius:  sqrt(2*(5+sqrt(5)))/4    ≈0.95105651629515357212
Midscribed Radius:  (1+sqrt(5))/4    ≈0.80901699437494742410
Inscribed Radius:  (3*sqrt(3)+sqrt(15))/12    ≈0.75576131407617073048
Volume:5*(3+sqrt(5))/12    ≈2.181694990624912373504