© Mio Tsugawa
Basic polyhedron is Dodecahedron which has 12 regular pentagons.
A part of the margin for paste, the triangular longest side is a half root 2.
Route 2 is the length of the diagonal of the square.
Half means it that when one side of the original paper of the square is considered to be 1, as for the length of one side of a completed polyhedron, it becomes a half routes 2.