¶ Spherical Icosahedron
← Sphere = Icosa | Spherical Icosahedron →
Index Entry
Spherical Icosahedron:
“We can take an icosahedron and put a sphere congruent to each of the 12 vertexes and if we place a light inside and project the shadows of the chords out on to the sphere, the result is a spherical icosahedron. The 20 equilateral triangles of the planar icosahedron can be symmetrically subdivided into six small right triangles by perpendicularly bisecting each angle. The angles of each small triangle are 90°, 60° and 30° and therefore each of the sides is different in length. In the spherical icosahedron, however, the angles are 90°, 60° and 36° with the last angle 60° more than the corresponding angle in the planar icosahedron. This is due to spherical excess.”
¶ Citations
- SYNERGETICS, “Numerology,” p. 13, Oct. '71.
