This article shows the necessity that there is, in an inclusive didactical study of the relationship to knowledge, to rely on a triangulation of theoretical approaches relating to the latter, through a case study, in particular that of the relationship to the Pythagoras’s Theorem, which study gave rise to the definition of a normative relationship, in acronym NiPADiS, for any knowledge and relative to the triangulation of theoretical approaches, namely anthropological, didactical and sociological approaches, to the relationship to knowledge.