I kept stepping though the pages till i found a thread un-answered.
you're on the right path. All u have to do, at least it's what i did, is parametrize your relation between delta and (x,y).
that is, consider the circle with radius about (5,2).
Then for any point (x,y) on the circle,
Now if we parametrize and to be functions of another variable , something i'm sure you've seen by now if you're in Calc III, then
Now pick an .
Set equal to the where are the roots of the equation: