Recall the dihedral group D = (o,p: p = = e.op=po). Show that if n is even then D, has normal subgroup of order 2 (note order, not index. You may find the fact that op = p o useful.) Recall the dihedral group D = (o,p: p = = e.op=po). Show that if n is even then D, has normal subgroup of order 2 (note order, not index. You may find the fact that op = p o useful.)