Solve for the offset of two sin waves

[NotASmurf]

Hey all, how does one solve sin(ax + by + c) = sin(ix + jy + d) for d and c if you only know the difference between d and c? Any help appreciated, simply arcsin'ing both sides does not work as you get impossible answers in the exact example I had.

 

[mfb]

You cannot solve it for both c and d, because the difference is the only thing that influences the equality. It's like trying to solve c=d+1 for both c and d - you cannot, you can only solve for the difference (here: 1).