2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/166038We describe the length spectra of triangle groups $(2,p,q)$ before showing that the length spectra characterizes the isometry class of such a group.29 pages, in french, to appear in Annales Institut FourierMetric Geometry20H10,32G15,53C22Les groupes de triangles $(2,p,q)$ sont détermineés par leur spectre des longueurstext