http://msmvps.com/blogs/visio/archive/2006/04/05/the-bowness-of-a-circular-arc.aspxTo create a circular arc in a shapesheet's Geometry section, requires the specification of where the arc ends and a cell called "A" that holds the measurement of how much the arc differs from a straight line between the end points of theenCommunityServer 2008.5 SP2 (Build: 40407.4157)