This article presents our analyses, in a didactical approach of the relationship to knowledge, from the didactic writings relating to situations of teaching-learning of the Pythagoras’s theorem, which writings have allowed us, with manual and official programs school most used in the DRC at the level of 3RD and 4th years secondary, to define, in terms of “3C relationships” [Rap1(Relationship of Knowledge), Rap2(Relationship of comprehension) and Rap3(Relationship of contextualisation)] relations that an individual or institution can maintain with the Pythagoras’s theorem, on the one hand; and put on feet, from the notes of 3C relationships defined in this study, three levels to appreciate the evolution of the relationship to knowledge of students to the Pythagoras’s theorem, including the level “low”, “medium” and “high”, on the other hand. This allows the operationalization of the relationship to knowledge on the didactical plan. The article also has some variables that we used to enjoy their possible influence on the relationship to knowledge in study, among students in the classes of Scientific Humanities of a school chosen to test the feasibility of the didactical study of 3C relationships.