(a) Let n = 2k be an even integer. Show that x = rkis an element of order 2 which commutes with every element ofDn.
(b) Let n = 2k be an even integer. Show that x = rkis the unique non-identity element which commutes with everyelement of Dn.
(c) If n is an odd integer, show that the identity is the onlyelement of Dn which commutes with every element ofDn.
