Need your help on how to determine the instantaneous power in a circuit with a supply of 230 V at a phase angle of 15°, and an impedance of 35ohms at 40°
You sure you want the instantaneous power and not the average power?
One way to do this would be to convert the specs into an actual circuit, then do a time domain analysis. That will allow you to calculate the instantaneous power anywhere from t=0 to t any time in the future.
To get the average power you can do an AC analysis once you convert the specs into a circuit.