What does it mean this notation?

[magodiafano]

The professor gave me this exercise, but since I am new in this subject I did not understand what he wants.

"In a single phase circuit Va=120 amplitude and 45degree as phase (written in polar form) and Vb = 100 amplitude and -15 phase.
Find Vba in polar form."

Does it mean that I have to do Vb-Va? or am I wrong?

 

[allennlowaton]

Your intuition is right. Just do the Vb-Va.

 

[chuckey]

You have to resolve both Va and Vb into their vertical and horizontal components. Add the horizs then the verts this gives you a new horiz and vert, turn back into Polar.
Frank