2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/96348We establish a connection between the uniform infinite planar triangulation and some critical time-reversed branching process. This allows to find a scaling limit for the principal boundary component of a ball of radius R for large R (i.e. for a boundary component separating the ball from infinity). We show also that outside of R-ball a contour exists that has length linear in R.27 pages, 5 figures, LaTeXProbabilityCombinatorics60C05; 60J80 (Primary); 05C30; 05C80 (Secondary)text