Points of coordinates:
are the 20 vertices of a regular dodecahedron of edge 2.
Where Phi is the golden ratio we've seen in the golden rectangle.
We can calculate the distance between pairs of adjacents vertices to convince ourselves.
This is an interesting step in understanding properties of this polyhedron, for example, the volume of a regular dodecahedron.
One eighth of a dodecahedron of side 2 has the same volume as a dodecahedron of side 1.