Hrrm. Did the last two parts today. Got my stone ring. Hooray for me. There were some difficulties along the way – such as me having missed the fact that if the absolute coordinates are both in the negative, one must ass 180 degrees to the resulting polar coordinate. I spent an hour figuring that one out – my sketches claimed I should go around 210-220 degrees, but my trusty OpenOffice Cals sheet claimed 32. 180 added to 32 is 212m which was right on the money.