I drew an approximate 90 degree arc, radius 5801 in 2D in Draft sight, and also opened it in Auto cad 2010.

Draft sight reported the arc length as 27394, area 9431206,start angle 180.584, start angle 269.998, end angle 180.584, total angle 0.586, radius 5801

Auto Cad reported the arc length as 9052, area 9431206, start angle 180.584, start angle 269.998, end angle 180.584, total angle 0.586, radius 5801

Draft sight arc length is obviously wrong - has anyone got an explanation?