Solution 5.8.6.1 Im(s) Re(s) X X α 1 β 1 ?α 1 ?β 1 Figure 1: Angles from Complex poles and zeros As can be seen from Figure 1, on the real axis, the angles from a pair of complex poles, or zeros, sum to zero, so they havenoe ect on the total angle of GH on the real axis. 1