And if you were to just poke a hole over here and put a third matchstick, you'll get a T joint. And if I were to poke all the three legs of this in the three vertices of this triangle, I would make a tetrahedron.
Si se perfora un agujero aquí y se le pone un fósforo, se obtiene una unión en T. Y si se colocan otros tres lados en los tres vértices del triángulo, tendremos un tetraedro.