I need to calculate the value of the resultant waveform at 45deg 120deg & 240deg that includes a third harmonic content of 20v.

Vmax is 200V, third harmonic amplitude is 20v

I know that to find the instantaneous voltage the calculation is:

e = Vmax sin0

So

e = 200 x sin 45 = 141.4V

e = 200 x sin 120 = 173.2V

e = 200 x sin 240 = -173.2V

Do I just ADD the 20v to each result to include the third harmonic amplitude or is there more to it?

Cheers