# Little Brother and Sister

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Picture copyright by
PhotoArt Studio HĂ¶rby
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These models were built in 2013 and their maximum dimensions are 8.5 cm x 8.5 cm x 8.5 cm.
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These polyhedra consist of regular heptagons that are allowed to be folded over
diagonals. There are different ways in which you can fold a regular heptagon and
for these polyhedra the folding is done in a 'W' shape.
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Both polyhedra are quite similar and quite different at the same time.
Around one type of symmetry axis the heptagons are arranged around the regular
squares or triangles as a dish, while for the other type of symmetry axis they
are aranged as a propeller. In both the models the role of the axes are
exchanged.
These models have the rotational symmetries from a cube (or octahedron).
A same kind of pair can be found for the dodecahedron (or icosahedron) symmetry.
Models of those can be found
here.
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I think they both have a pleasing shape and they form a nice pair.
The choice of which one is brother and which one sister is based on the
following:
the propeller with three blades reminds me of a Y chromosome (brother) while the
one with four reminds me of an X chromosome (sister).
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## Last Updated

2022-01-10