A new geometric condition equivalent to the maximum angle condition for tetrahedrons

For a tetrahedron, suppose that all internal angles of faces and dihedral are less than fixed constant $C$ is smaller $\pi$. Then, it said to satisfy the maximum angle condition with $C$. The important in error analysis Lagrange interpolation on tetrahedrons. This ensures we can obtain an estimation, even certain kinds anisotropic In this paper, using two quantities represent geometry tetrahedrons, present equivalent geometric for