Let us recall that the Tetrahedron is four-faced Symmetric Solid Object with exactly four (4) [ nodal-points ] , and :
- the 4 [ nodal-points ] are all equi-distant from the [ centroid ] of Symmetric Solid Object .

This then permits us to put the 4 [ nodal-points ] onto the surface of a Sphere , so that :
- the 4 [ nodal-points ] are now all equi-distant from the [ center ] of the Sphere .