Partition a line segment so that the difference between the square on the greater part and the square on the lesser part is constant.
AK^2 - KD^2 = AC^2, AC is of fixed length">
In the figure, point K splits AD into AK and KD, such that $AK^2 - KD^2 = AC^2$, AC is of fixed length.
Can this be achieve by compass and straight edge?