Icosahedron のコピー
Sometimes regular... The vertices of 3 orthogonal congruent rectangles can be
connected to make a polyhedron with 20 triangular faces
(icosahedron). One of the most wonderful facts of geometry
is that if those rectangles have the golden proportion, it's the
regular icosahedron - a platonic solid!
More GeoGebra at bit.ly/mh-ggb