E7.19 A unity feedback system has a loop transfer function

K L(s) = G(s)G(s) = s(s+3)(s + 6s+64) (a) Determine the angle of departure of the root locus at the complex poles. (b) Sketch the root locus. (c) Determine the gain K when the roots are on the jw-axis and determine the location of these roots.