def FacesTetraedre(R):
    """returns the faces of the tetraedre"""
    F1 = R[0], R[1], R[2]
    F2 = R[1], R[2], R[3]
    F3 = R[2], R[0], R[3]
    F4 = R[3], R[1], R[0]
    Faces = F1, F2, F3, F4
    return Faces
