Power triangle

In power analysis, the power triangle is a useful diagram that captures the relations between average and reactive power and relevant angles. The power factor angle is $\theta$, the angle by which the voltage leads the current.

$$\theta ={\varphi }_V-{\varphi }_I$$

where ${\text{I}}_A=I_A\angle {\varphi }_I$ and ${\text{V}}_A=V_A\angle {\varphi }_V$.