A polyhedron bounded by twenty equilateral triangles; five meeting at each vertex.
The icosahdedron is one of the five platonic solids.
|35||5 | 2 3||12||30||20||A5×C2||Dodecahedron|
- `e/r = sqrt(3) (3-sqrt(5))`
- `e/rho = sqrt(5)-1`
- `e/R = sqrt((10-2sqrt(5))/5)`