2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/67889We prove that the difference between 1 and the conformal radius at 0 of the universal covering of a big open subset U of the unit disk in the complex plane is comparable to the area of a union of triangles constucted from the complement of U. We apply this to corret a lemma in the thesis of the author. ----- Nous prouvons que la difference entre 1 et le rayon conforme en 0 du revetement universel d'un grand ouvert U du disque unite du plan complexe est comparable a l'aire d'une reunion de triangles construits a partir du complementaire de U. Nous appliquons cela a la correction d'un lemme de la these de l'auteur.14 pages, in French. This update corrects a problem with the automatically generated PDF versionDynamical Systems30C85 (Primary) 30C2X, 37FXX (Secondary)text