Re: three phase
Yes. Divide 208 by the square root of three (1.732) and you get 120.
If you want to know where the square root of three comes from, then draw two arrows of equal length (make it 120 centimeters), with their begining points at the same location, and their arrows pointing out at an angle of 120 degrees from each other. Then measure the distance between the arrow tips. You should get about 208 cm, an increase of a factor of 1.73. What you would be modeling is the phase to phase voltages (208) and the phase to neutral voltages (120), with an angle of 120 degrees between phases.