This quality parameter applies to tetra, hexa, quad, and tri elements.
Element equiangle skew = 1.0 – max ((Qmax – Qe) / (180 – Qe), (Qe – Qmin) / Qe),
where
Qmax = largest angle in the face or element
Qmin = smallest angle in the face or element
Qe = angle of an equiangular face or element (60 degrees for a triangle or 90 degrees for a square).