El proceso de definir en matemáticas. Un caso : el triángulo

Departing from two protocols that show the difficulties presented to define the triangle in primary school pupils, and through a theoretical framework based on Orton (1990), Herskhovits (1990), Tall and Vinner (1981) and Van Hiele (1981) to establish the meaning that the definition has in Mathematics, we accomplish a summary of definitions of the concept of triangle in various original texts, as well as in material and computer programs. A short analysis of the definitions presented is accomplished and we offer certain theoretical evaluations to justify the answers given by the students