10.1 For each of the following groups of sources, determine if the three sources constitute a balanced source, and if it is, determine if it has a positive or negative phase sequence. (a) a(t) = 169.7 cos(377t 15) V b(t) = 169.7 cos(377t 105) V c(t) = 169.7 sin(377t 135) V (b) a(t) = 311 cos(t 12) V b(t) = 311 cos(t 108) V c(t) = 311 cos(t 228) V (c) V1 = 140 140 V V2 = 114 20 V V3 = 124 100 V