EULER CHARACTERISTIC FOR TEACHERS

In the present paper we explain the well-known Euler formula for solids, as an interesting argument to be dealt with students, in order to point out that in mathematics, and particularly in geometry, there are many different ways to investigate objects. It is also explained with examples the topological reason for which, in defining the Euler Characteristic of a polyhedral surface in the space, it is necessary to use a triangulation, instead of a general tassellation