## Pentagonal Dipyramid

The pentagonal dipyramid is one of the convex Deltahedra, and Johnson Solid . It is also the Dual Polyhedron of the Pentagonal Prism. The distance between two adjacent Vertices on the base of the Pentagon is

 (1)

and the distance between the apex and one of the base points is
 (2)

But
 (3)

 (4)

 (5)

and
 (6)

This root is of the form , so applying Square Root simplification gives
 (7)

where is the Golden Mean.