Show that no two-dimensional Bravais lattice can have a 5- or 7-fold axis of rotation, i.e., no axis such that a rotation by 2/5 or

Show that no two-dimensional Bravais lattice can have a 5- or 7-fold axis of rotation, i.e., no axis such that a rotation by 2π/5 or 2π/7 leaves that lattice invariant.