But does it have its limitations?

For example:

*A capacitor C is connected in series with 40*Ω

*resistor across a supply of freq. 60Hz. A current of 3A flows and the circuit Z is 50*Ω.

*Value of capacitance?*

I cant see a way of using polar notation - the only way I can see to solve this question is to have to draw phasor diagrams, then use trig./pythag. theorems

*?*