Pentagonal gyrobicupola explained

Type:Bicupola,
Johnson
Faces:10 triangles
10 squares
2 pentagons
Edges:40
Vertices:20
Symmetry:

D5

Vertex Config:

10 x (3 x 4 x 3 x 4)


10 x (3 x 4 x 5 x 4)

Net:Johnson solid 31 net.png

The pentagonal gyrobicupola is a polyhedron that is constructed by attaching two pentagonal cupolas base-to-base, each of its cupolas is twisted at 36°. It is an example of a Johnson solid and a composite polyhedron.

Construction

The pentagonal gyrobicupola is a composite polyhedron: it is constructed by attaching two pentagonal cupolas base-to-base. This construction is similar to the pentagonal orthobicupola; the difference is that one of cupolas in the pentagonal gyrobicupola is twisted at 36°, as suggested by the prefix gyro-. The resulting polyhedron has the same faces as the pentagonal orthobicupola does: those cupolas cover their decagonal bases, replacing it with eight equilateral triangles, eight squares, and two regular pentagons. A convex polyhedron in which all of its faces are regular polygons is the Johnson solid. The pentagonal gyrobicupola has such these, enumerating it as the thirty-first Johnson solid

J31

.

Properties

Because it has a similar construction as the pentagonal orthobicupola, the surface area of a pentagonal gyrobicupola

A

is the sum of polygonal faces' area, and its volume

V

is twice the volume of a pentagonal cupola for which slicing it into those: \begin A &= \fraca^2 \approx 17.771a^2, \\ V &= \fraca^3 \approx 4.648a^3.\end

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Pentagonal gyrobicupola".

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