V1 + V2 = Vx

V1 + V2 + V3 = Vy,

where Vx, V3, and Vy have been measured with reasonable accuracy, maybe +/-2%

Any thoughts on how to approach? If, for example, if I convert to rectangular form and try substitution the entire thing is quickly swimming in a sea of sines and cosines that cannot possibly be solvable

My question is this: There should be enough known to solve, is that right? Can this just go into a matrix and get solved that way?

thanks for any help