Acronym	stai
Name	small triambic icosahedron, first stellation of the icosahedron
	© ©
Inradius	[3+sqrt(5)]/[2 sqrt(30)] = 0.477985
Vertex figure	[h3], [H5]/2
Dual	sidtid
Dihedral angles (at margins)	between {(h,H)3} and {(h,H)3}:   arccos(-1/3) = 109.471221°
Face vector	32, 60, 20
External links

The shields {(h,H)³} have vertex angles h = arccos(-1/4) = 104.477512° resp. H = arccos[-(3 sqrt(5)-1)/8] = 135.522488°. Esp. HH : hh = [3+sqrt(5)]/[2 sqrt(5)] = 1.170820.

Incidence matrix

12  * |  5 |  5		[H5]/2
 * 20 |  3 |  3		[h3]
------+----+---
 1  1 | 60 |  2
------+----+---
 3  3 |  6 | 20		{(h,H)3}