2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56466It is proved that if the scattering amplitudes at a fixed wavenumber for two obstacles from a certain large class of obstacles differ a little, than the obstacles differ a little. Error estimate is given. It is proved that there is an inversion formula for finding the obstacle from a fixed-energy scattering data.Mathematical PhysicsAnalysis of PDEs35R30, 73D50text