11.1 What is the phase sequence of each of the following sets of voltages? = a) va 137 cos (wt + 63) V, vb = Vc = = 137 cos (wt 57) V, 137 cos (wt 183) V. b) va 820 cos (wt - 36) V, Vb === 820 cos (wt 84) V, = vc 820 sin (wt - 66) V. Vc