Земляк, можно и так:
public static IGeometry GeometryCreateCircle(IPointCollection[] PointCollArr)
{
try
{
object Miss = Type.Missing;
ICircularArc Circle = new CircularArcClass();
IConstructCircularArc construtionCircularArc = Circle as IConstructCircularArc;
IPoint CentrPoint = PointCollArr[0].get_Point(0);
IPoint OtherPoint = PointCollArr[0].get_Point(1);
construtionCircularArc.ConstructCircle(CentrPoint, OtherPoint.Y, false);// OtherPoint.Y это радиус
ISegmentCollection SegColl = new PolygonClass();
ISegment seg = construtionCircularArc as ISegment;
SegColl.AddSegment(seg, ref Miss, ref Miss);
IGeometry g = SegColl as IGeometry;
return g;
}
catch (Exception ex)
{
Error.SaveError(ex);
return null;
}
}