The comprehension of the trigonometrical reasons by means of the software GeoGebra in the context of the model of Van Hiele is an offer that searches by means of a study of cases, analyzes the comprehension of the trigonometrical reasons of the students of degree 10, where there arise contributions and such important elements as the used language and the meaning of the geometric and trigonometrical contents, pass through for certain processes of thought and levels of knowledge, well–balanced in experiences inside the practices of classroom. keeping in mind that the joint of the model in mind of Van Hiele with the concepts and pre-concepts established for the comprehension of the trigonometrical reasons, they arise hypothetical describers of the levels of reasoning by Van Hiele, thanks to the results of a diagnostic test and the questions related to the visualization of elements elaborated by means of the software GeoGebra. These strategies allow to deduce in what level the students are and this way from a module of learning there is claimed that they advance from a level to other one, by means of a series of cognitive activities in relation with the comprehension and the phases of learning of Van Hiele.
