There are several Archimedean solids that are formed by the truncation (cutting off) of each corner of a Platonic solid. These can be shown in successive truncations from one shape to its dual. Original Truncation Rectification Bitruncation Birectification (dual) Tetrahedron Truncated Tetrahedron **…Read the Rest**

## Tag: icosahedron

### Icosahedron

2015-01-29

The icosahedron has 12 equilateral triangles as faces. It can be split into 3 parts, a pentagonal anti-prism and two pentagonal pyramids. We will start by looking at a pentagonal pyramid. We have already done most of the work earlier. To find ∠ACB, $$\begin{align}\cos \angle **…Read the Rest**