Hi,

what about something along these lines. Set A to coordinates (0,0) and B to coordinates (0, 633).

Say C has coordinates (x, y).

You have:

sqrt (x² + y²) = 257
sqrt(x² + (633 - y)²) = 390
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Solving this system of two equations is straight forward. (Hoping I did not goof the maths ;-) For the next points, one needs to be a bit more general and use the distances to A, B and C.