1.   This phasor diagram is similar to Fig.

2.   Drawing the phasor diagram that satisfies the magnitudes of these three potential differences, however, establishes the relative phases.

3.   The resistance R and reactance X therefore follow from application of the relations For good accuracy, needs to be similar in magnitude to R and X.

4.   Of course, the r.m.s. current could be measured separately by inserting a suitable a.c. meter in series with the circuit.

5.   As an alternative to drawing the phasor diagram, an analytic solution is possible for and in terms of the measurements.