Resumen de Orthogonality in the hyperbolic plane
Domingo Gámez Domingo, Miguel Pasadas Fernández 
, Rafael Pérez García
Guidelines for an analytical treatment of the small-amplitude orbital motion of a particle of negligible (infinitesimal) mass about the libration points in the planar elliptic restricted three-body problem (ERTBP) are outlined. Keywords: In this paper three essential construction are considered, construction which involve the orthogonality in the models of Poincaré for the hyperbolic plane: a) Determination of the line orthogonal to another one given through a point of it. b) Determination of the unique orthogonal line to a pair of ultraparallel lines. c) Determination of the line orthogonal to another one given through an outer point. This construction apply to the resolution of many problems of the plane hyperbolic geometry.
