Revolve sketch with arc

var sk1 = new devDept.Geometry.ConstraintSolver.Sketch();

// Create the linear border.
var l1 = sk1.AddLine(0, 0, 20, 0);
var l2 = sk1.AddLine(20, 0, 20, 10);
var l3 = sk1.AddLine(20, 10, 12.4142, 10);
var l4 = sk1.AddLine(11.7071, 11.7071, 20, 20);
var l5 = sk1.AddLine(20, 20, 0, 20);
var l6 = sk1.AddLine(0, 20, 0, 0);

// Create the connection arc.
Arc arc = new Arc(  new Point3D(12.4142, 11, 0), 
                    new Point3D(12.4142, 10, 0), 
                    new Point3D(11.7071, 11.7071, 0));
// Arcs in a sketch are always considered as counter-clockwise 
// according to the normal of the sketch plane.
if(Vector3D.AreOpposite(arc.Plane.AxisZ, sk1.SketchPlane.AxisZ))
    arc.Reverse();

var a1 = sk1.AddArc(arc.Center, arc.StartPoint, arc.EndPoint);

// Hor/Ver constraints.
sk1.AddConstraintHorizontal(l1);
sk1.AddConstraintHorizontal(l3);
sk1.AddConstraintHorizontal(l5);
sk1.AddConstraintVertical(l2);
sk1.AddConstraintVertical(l6);

// Tangency between the arc and connected linear segments.
sk1.AddConstraintTangent(l3, a1);
sk1.AddConstraintTangent(a1, l4);

// Fix side lenghts.
sk1.AddConstraintLength(l1, 20);
sk1.AddConstraintLength(l2, 10);
sk1.AddConstraintLength(l5, 20);
sk1.AddConstraintLength(l6, 20);

// Ensure continuity between all sides.
sk1.AddConstraintJoin(l3.EndPoint, a1.EndPoint);
sk1.AddConstraintJoin(l4.StartPoint, a1.StartPoint);
sk1.AddConstraintJoin(l1.EndPoint, l2.StartPoint);
sk1.AddConstraintJoin(l2.EndPoint, l3.StartPoint);
sk1.AddConstraintJoin(l4.EndPoint, l5.StartPoint);
sk1.AddConstraintJoin(l5.EndPoint, l6.StartPoint);
sk1.AddConstraintJoin(l6.EndPoint, l1.StartPoint);

// Fix the arc angle and radius.
sk1.AddConstraintAngle(l3, l4);
sk1.AddConstraintRadius(a1);

// Fix the first point location.
sk1.AddFixedPointConstraint(l1.StartPoint);

// Create a BRep via revolution.
Brep tool = new Brep(sk1.RevolveAsBrep(UtilityEx.TWO_PI, Vector3D.AxisY, new Point3D()));
design1.Entities.Add(tool, Color.DarkGray);