Relativistic reactions visualized through right triangles in space

In this article we exploit the fact that the special relativistic formula which relates the energy and the 3-momentum of an elementary particle with its rest mass, resembles the pythagorean theorem for right triangles. Using such triangles, suitably arranged, we can prove all kind of equalities or inequalities concerning the kinematical properties of elementary particles in a wide variety of cases regarding particles' collision, decay or production. Moreover, relations that are somehow hard to produce by the usual analytic methods arise much more naturally through geometric constructions based on right triangles.