PolyhedronAngle

PolyhedronAngle[poly,p] gives the solid angle at the point p and spanned by edges with common point p.

PolyhedronAngle[poly,e] gives the dihedral angle between the two faces with common edge e.

Examples

Find the solid angle at a vertex of a tetrahedron:

PolyhedronAngle[Tetrahedron[], {0, 0, 0}]

Please visit the official Wolfram Language Reference for more details.