The dihedral angles in this solid have an angle equal to the arccosine of negative root five over three, which is about 138 degrees.
The dihedral angles in this solid have an angle equal to the arccosine of negative root five over three, which is about 138 degrees. All of its vertices can be sorted into groups of four that form golden rectangles. One of these solids with side length two can be placed in rectangular coordinates so that each point has one coordinate equal to zero, one coordinate equal to plus or minus one, and one coordinate equal to the golden ratio. It contains thirty edges and twelve vertices, and each vertex brings together five triangles. Name this platonic solid, the dual of the dodecahedron, whose name is derived from the Greek for twenty because it has twenty sides.
The dihedral angles in this solid have an angle equal to the arccosine of negative root five over three, which is about 138 degrees.
{icosahedron}