Other Solids

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Associahedron (canonical)
Vertices:  14  (2[3] + 6[3] + 6[3])
Faces:9  (3 squares + 6 mirror-symmetric pentagons)
Edges:21  (15 short + 6 long)
Symmetry:  3-fold Prismatic  (D3h)
Pentagon-Pentagon Angle:  acos(−1/7)    ≈98.213210702 degrees
Pentagon-Square Angle:  acos(−sqrt(7)/7)    ≈112.207654299 degrees
(values below based on long edge length = 2)
Short Edge (15):  3*(2−sqrt(2))    ≈1.7573593128807148536
Long Edge (6):  2
5-5-5 Vertex Radius (2):  3*sqrt(2)−2    ≈2.2426406871192851464
4-5-5 Vertex Radius (12):  sqrt(6*(5−3*sqrt(2)))    ≈2.1317025771163033244
Pentagon Plane Radius:  (3*sqrt(42)−2*sqrt(21))/7    ≈1.4681529579017000971
Square Plane Radius:  sqrt(3)    ≈1.73205080756887729353
Edge-scribed Radius:  (3*sqrt(6)−2*sqrt(3))/2    ≈1.9421838066058898538
Volume:3*(68*sqrt(3)−45*sqrt(6))    ≈22.657249468321924623


References:[1]James Dillon Stasheff, Homotopy Associativity of H-spaces, I and II,
Transactions of the American Mathematical Society 108 (1963), 275-312.
[2]The 3-Dimensional Associahedron
[3]Canonical Polyhedron (Wolfram MathWorld)