=+6. to determine the multiplicity of the eigenvalue and interpret the physical nature of the corresponding eigenmodes at the light of the degeneracy theorem on multiple eigenvalues (Section 2.3.2).

Note: in the present case the surface integrals involved in the computation of the strain and kinetic energies of the plate can be obtained in closed form (in which case it is advised to use symbolic computation), but it is far more efficient to compute them through numerical quadrature.