28. Find the average power loss and power factor for each of the circuits whose input current and voltage are as follows: a. v = 60 sin(wt + 30°) i = 15 sin(wt + 60°) b. v=-50 sin(wt - 20°) i = -2 sin(wt - 20°) c. v = 50 sin(wt + 80°) i = 3 cos(wt - 20°) d. v=75 sin(wt 5°) i = 0.08 sin(wt + 35°)