When complex number represent stationary AC signal, it is called phasor. Complex number and so phasor can be presented with two equivalent notifications:
- Cartesian coordinates
- Polar coordinates
Knowing exponential representative of complex number, we have relation between complex number and trigonometric functions as
So, if we have two sine or cosine signals with some phase, it is easy to obtain their sum or difference via Cartesian coordinates of AC signal complex representatives. Online addition and subtraction of complex numbers together with time domain waveforms can be done on following links:
In AC electrical theory we need to add two or more trigonometric currents that flow in/from given node, or to add two or more trigonometric voltages. Utilization of phasor for that purpose is very practical thing.