Regular Icosahedron ( inscribed sphere radius)

Description

An icosahedron is a polyhedron with 20 triangular faces, 30 edges and 12 vertices. A regular icosahedron has 20 identical equilateral faces, with five of the triangular faces meeting at each vertex. If the edge length of a regular icosahedron is “a”,the radius of an inscribed sphere (tangent to each of the icosahedron’s faces) is related to the edge length of the triangle face and the “golden ratio”.