2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/79215An upper bound on the first S^1 invariant eigenvalue of the Laplacian for invariant metrics on the 2-sphere is used to find obstructions to the existence of isometric embeddings of such metrics in (R^3,can). As a corollary we prove: If the first four distinct eigenvalues have even multiplicities then the surface of revolution cannot be isometrically embedded in (R^3,can). This leads to a generalization of a classical result in the theory of surfaces.Latex, 11 pages New version contains a new reference and minor stylistic changesDifferential Geometry58G25, 58G30 (Primary) 35P15 (Secondary)text