2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78895We give a stereological version of the Gauss-Bonnet formula in order to compute the Euler characteristic of a domain with boundary in a smooth orientable surface in R^3, by looking at contacts with a "sweeping" plane.6 pages; 2 figures; AMS-LaTeXDifferential Geometry53C65text