Great inverted pentagonal hexecontahedron

The great inverted pentagonal hexecontahedron is a uniform dual polyhedron. It consists of 60 mirror-symmetric concave pentagons, each with two short and three long edges.

If its dual, the great inverted snub icosidodecahedron, has unit edge length, then the pentagon faces' short edges have approximate length 0.23186 (equal to a root of the polynomial $$31x^6-53x^5-26x^4+34x^3+17x^2-x-1$$), and the long edges have approximate length 0.81801 (equal to a root of the polynomial $$x^6-2x^5-4x^4+x^3+4x^2-1$$).

A dihedral angle can be given as acos(α), where α ≈ 0.20178 is a real root of the polynomial $$209x^6-94x^5-137x^4+100x^3-9x^2-6x+1$$.

The inradius R ≈ 0.25744 of the great inverted pentagonal hexecontahedron with unit edge length is equal to the square root of a real root of $$856064x^6-3900416x^5+1443072x^4-149376x^3+6384x^2-128x+1$$.