Pentagonal icositetrahedron

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Pentagonal icositetrahedron
Pentagonal icositetrahedron, anticlockwise twistPentagonal icositetrahedron
Click ccw or cw for spinning versions.
Type Catalan
Conway notation gC
Coxeter diagram CDel node fh.pngCDel 4.pngCDel node fh.pngCDel 3.pngCDel node fh.png
Face polygon DU12 facets.png
irregular pentagon
Faces 24
Edges 60
Vertices 38 = 6 + 8 + 24
Face configuration V3.
Dihedral angle 136° 18' 33'
Symmetry group O, ½BC3, [4,3]+, 432
Dual polyhedron snub cube
Properties convex, face-transitive, chiral
Pentagonal icositetrahedron

In geometry, a pentagonal icositetrahedron or pentagonal icosikaitetrahedron[1] is a Catalan solid which is the dual of the snub cube. In crystallography it is also called a gyroid.[2][3]

It has two distinct forms, which are mirror images (or "enantiomorphs") of each other.


Denote the tribonacci constant by t, approximately 1.8393. (See snub cube for a geometric explanation of the tribonacci constant.) Then the pentagonal faces have four angles of \cos^{-1}\left(\frac{1-t}{2}\right)\approx 114.8° and one angle of \cos^{-1}(2-t)\approx 80.75°. The pentagon has three short edges of unit length each, and two long edges of length \frac{t+1}{2}\approx1.42. The acute angle is between the two long edges.

If its dual snub cube has unit edge length, its surface area is \scriptstyle{3}\sqrt{\tfrac{22(5t-1)}{4t-3}} \scriptstyle{\approx 19.29994} and its volume is \sqrt{\tfrac{11(t-4)}{2(20t-37)}} \scriptstyle{\approx 7.4474}.[4]

Orthogonal projections[edit]

The pentagonal icositetrahedron has three symmetry positions, two centered on vertices, and one on midedge.

Orthogonal projections
[3] [4]+ [2]
Image Dual snub cube A2.png Dual snub cube B2.png Dual snub cube e1.png
Snub cube A2.png Snub cube B2.png Snub cube e1.png

Related polyhedra and tilings[edit]

Spherical pentagonal icositetrahedron

This polyhedron is topologically related as a part of sequence of polyhedra and tilings of pentagons with face configurations (V3.3.3.3.n). (The sequence progresses into tilings the hyperbolic plane to any n.) These face-transitive figures have (n32) rotational symmetry.

n32 symmetry mutations of snub tilings:
Spherical Euclidean Compact hyperbolic Paracomp.
232 332 432 532 632 732 832 ∞32
Spherical trigonal antiprism.png Spherical snub tetrahedron.png Spherical snub cube.png Spherical snub dodecahedron.png Uniform tiling 63-snub.png Uniform tiling 73-snub.png Uniform tiling 83-snub.png Uniform tiling i32-snub.png
Uniform tiling 432-t0.png Uniform tiling 532-t0.png Spherical pentagonal icositetrahedron.png Spherical pentagonal hexecontahedron.png Tiling Dual Semiregular V3-3-3-3-6 Floret Pentagonal.svg Ord7 3 floret penta til.png Order-3-infinite floret pentagonal tiling.png
Config. V3. V3. V3. V3. V3. V3. V3. V3.3.3.3.∞

The pentagonal icositetrahedron is second in a series of dual snub polyhedra and tilings with face configuration V3.3.4.3.n.

4n2 symmetry mutations of snub tilings:
Spherical Euclidean Compact hyperbolic Paracomp.
242 342 442 542 642 742 842 ∞42
Spherical square antiprism.png Spherical snub cube.png Uniform tiling 44-snub.png Uniform tiling 54-snub.png Uniform tiling 64-snub.png Uniform tiling 74-snub.png Uniform tiling 84-snub.png Uniform tiling i42-snub.png
Spherical tetragonal trapezohedron.png Spherical pentagonal icositetrahedron.png Tiling Dual Semiregular V3-3-4-3-4 Cairo Pentagonal.svg Order-5-4 floret pentagonal tiling.png
Config. V3. V3. V3. V3. V3. V3. V3. V3.3.4.3.∞

The pentagonal icositetrahedron is one of a family of duals to the uniform polyhedra related to the cube and regular octahedron.


External links[edit]