Icosahedron
object · 1 work · 2 mentions · 8 anchored passages
icosahedron · the icosahedron
in the texts
Elements
One of the five regular (Platonic) solids, attributed to Theaetetus, discussed via comparison to the dodecahedron.
After Euclid, Apollonius wrote on the comparison of the dodecahedron and the icosahedron inscribed in one and the same sphere.
The same circle circumscribes both the pentagon of the dodecahedron and the triangle of the icosahedron when both are inscribed in the same sphere.
says that the Book is about the five so-called Platonic figures, which however do not belong to Plato, three of the aforesaid five figures being due to the Pythagoreans, namely the cube, the pyramid and the dodecahedron, while the octahedron and the icosahedron are due to Theaetetus.