I'm drawing some ROIs in an application I wrote and I'd like to find
the largest diameter, and its largest perpendicular diameter. Finding
the largest diameter of the ROI is easy, but finding its largest
perpendicular diameter is a little more difficult.

Initially I just found the slope of the perpendicular line to the
largest diameter, and searched through all available x,y pairs to see
if any had that perpendicular slope. Of those, I would pick the pair
with the longest length.

Since my points are being captured on a screen, I just have these
integer values to work with. Any ideas how I could use these x/y points
to find the max perpendicular diameter?