I understand power factor is defined as (average power)/(apparent power) or cos(theta v - theta i) where theta v = load voltage and theta i = load current. Also the power factor angle is equal to the load impedance.
I don't understand how the 2 definitions of power factor equal each other or why the power factor angle equals the load impedance.
I know it's a tall order but I would appreciate it if somebody could answer these questions. Alternatively a good website or book that explains this fully.