A coincidence in geometry:
Take a regular dodecahedron (yellow) and a regular octagon (blue), both with edge length 1. When they are concentric, some of the octagon's vertices seem to coincide with the centres of the dodecahedron's edges (see black circle).
But actually the dodecahedron's midradius is (3+√5)/4 or ~1.309, while the octagon's circumradius is just 1/√(2−√2) or ~1.307.













