Star Dipyramids & Trapezohedra

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Pentagrammic Dipyramid
Vertices:  7  (5[4] + 2[5])
Faces:10  (isosceles triangles)
Edges:15  (10 short + 5 long)
Symmetry:  5-fold Prismatic  (D5h)
Dihedral Angle:  acos(−(11−4*sqrt(5))/41)    ≈92.873998801 degrees
Dual Solid:  Pentagrammic Prism
(values below based on unit-edge-length Pentagrammic Prism)
Short Edge (10):  4*sqrt(5)/5    ≈1.7888543819998317571
Long Edge (5):  1+sqrt(5)    ≈3.2360679774997896964
[5]-Vertex Radius (2):  (5−sqrt(5))/5    ≈0.55278640450004206072
[4]-Vertex Radius (5):  sqrt(10*(5+sqrt(5)))/5    ≈1.7013016167040798644
Edge-scribed Radius:  sqrt(10*(5−sqrt(5)))/10    ≈0.52573111211913360603
Inscribed Radius:  sqrt(410*(35−9*sqrt(5)))/205    ≈0.38095372233513360886