public enum ArcOrientation : System.Enum, System.IComparable, System.IConvertible, System.IFormattable  

MapPoint startPoint = MapPointBuilderEx.CreateMapPoint(0, 0);
MapPoint queryPoint = MapPointBuilderEx.CreateMapPoint(3.8, 1);
double tangentDirection = 0;
ArcOrientation orientation = ArcOrientation.ArcCounterClockwise;
double startRadius = double.PositiveInfinity;
double endRadius = 1;
ClothoidCreateMethod createMethod = ClothoidCreateMethod.ByLength;
double curveLength = 10;
MapPoint pointOnPath;
double radiusCalculated, tangentDirectionCalculated, lengthCalculated, angleCalculated;


PolylineBuilderEx.QueryClothoidParameters(queryPoint, startPoint, tangentDirection, startRadius, endRadius, orientation, createMethod, curveLength, out pointOnPath, out radiusCalculated, out tangentDirectionCalculated, out lengthCalculated, out angleCalculated, SpatialReferences.WGS84);

pointOnPath = MapPointBuilderEx.CreateMapPoint(3.7652656620171379, 1.0332006103128575);
radiusCalculated = 2.4876382887687227;
tangentDirectionCalculated = 0.80797056423543978;
lengthCalculated = 4.0198770235802987;
angleCalculated = 0.80797056423544011;

queryPoint = MapPointBuilderEx.CreateMapPoint(1.85, 2.6);

PolylineBuilderEx.QueryClothoidParameters(queryPoint, startPoint, tangentDirection, startRadius, endRadius, orientation, createMethod, curveLength, out pointOnPath, out radiusCalculated, out tangentDirectionCalculated, out lengthCalculated, out angleCalculated, SpatialReferences.WGS84);

pointOnPath = MapPointBuilderEx.CreateMapPoint(1.8409964973501549, 2.6115979967308132);
radiusCalculated = 1;
tangentDirectionCalculated = -1.2831853071795867;
lengthCalculated = 10;
angleCalculated = 5;
 
tangentDirection = Math.PI / 4;
orientation = ArcOrientation.ArcClockwise;
startRadius = double.PositiveInfinity;
endRadius = 0.8;
createMethod = ClothoidCreateMethod.ByLength;
curveLength = 10;

Polyline polyline = PolylineBuilderEx.CreatePolyline(startPoint, tangentDirection, startRadius, endRadius, orientation, createMethod, curveLength, CurveDensifyMethod.ByLength, 0.5, SpatialReferences.WGS84);

// Construct a circle with center at (-1,-1), radius = 2, and oriented clockwise.
// Use a builderEx convenience method or use a builderEx constructor.

Coordinate2D centerPtCoord = new Coordinate2D(-1, -1);

// Builder convenience methods don't need to run on the MCT.
EllipticArcSegment circle = EllipticArcBuilderEx.CreateCircle(centerPtCoord, 2, ArcOrientation.ArcClockwise);
// circle.IsCircular = true
// circle.IsCounterClockwise = false
// circle.IsMinor = false

double startAngle, rotationAngle, centralAngle, semiMajor, semiMinor;
Coordinate2D actualCenterPt;
circle.QueryCoords(out actualCenterPt, out startAngle, out centralAngle, out rotationAngle, out semiMajor, out semiMinor);

// semiMajor = 2.0
// semiMinor = 2.0
// startAngle = PI/2
// centralAngle = -2*PI
// rotationAngle = 0
// endAngle = PI/2

// This EllipticArcBuilderEx constructor doesn't need to run on the MCT.
EllipticArcBuilderEx builder = new EllipticArcBuilderEx(centerPtCoord, 2, ArcOrientation.ArcClockwise);
EllipticArcSegment otherCircle = builder.ToSegment();

//Create a circle graphic element using a simple line and fill styles.

//Construct on the worker thread
await QueuedTask.Run(() =>
{
  //Build geometry
  Coordinate2D center = new Coordinate2D(2, 4);
  //At 2.x - EllipticArcBuilder eabCir = new EllipticArcBuilder(center, 0.5, esriArcOrientation.esriArcClockwise);
  var eabCir = new EllipticArcBuilderEx(center, 0.5, ArcOrientation.ArcClockwise);
  EllipticArcSegment cir = eabCir.ToSegment();

  //Set symbolology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.BlackRGB, 2.0, SimpleLineStyle.Dash);
  CIMPolygonSymbol circleSym = SymbolFactory.Instance.ConstructPolygonSymbol(ColorFactory.Instance.RedRGB, SimpleFillStyle.Solid, outline);
  //At 2.x - GraphicElement cirElm = LayoutElementFactory.Instance.CreateCircleGraphicElement(layout, cir, circleSym);
  //         cirElm.SetName("New Circle");

  var polyLine = PolylineBuilderEx.CreatePolyline(cir);
  GraphicElement cirElm = ElementFactory.Instance.CreateGraphicElement(layout, polyLine, circleSym, "New Circle");
});

//Create an ellipse graphic with simple line and fill styles.

//Construct on the worker thread
await QueuedTask.Run(() =>
{
  //Build geometry
  Coordinate2D center = new Coordinate2D(2, 2.75);
  //At 2.x - EllipticArcBuilder eabElp = new EllipticArcBuilder(center, 0, 1, 0.45, esriArcOrientation.esriArcClockwise);
  var eabElp = new EllipticArcBuilderEx(center, 0, 1, 0.45, ArcOrientation.ArcClockwise);
  EllipticArcSegment ellipse = eabElp.ToSegment();

  //Set symbolology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.GreenRGB, 2.0, SimpleLineStyle.Dot);
  CIMPolygonSymbol ellipseSym = SymbolFactory.Instance.ConstructPolygonSymbol(ColorFactory.Instance.GreyRGB, SimpleFillStyle.Vertical, outline);
  //At 2.x - GraphicElement elpElm = LayoutElementFactory.Instance.CreateEllipseGraphicElement(layout, ellipse, ellipseSym);
  //         elpElm.SetName("New Ellipse");

  var polyLine = PolylineBuilderEx.CreatePolyline(ellipse);
  GraphicElement elpElm = ElementFactory.Instance.CreateGraphicElement(layout, polyLine, ellipseSym, "New Ellipse");
});

//Must be on QueuedTask.Run(() => { ...

//Build geometry
Coordinate2D center = new Coordinate2D(2, 4);
EllipticArcSegment circle_seg = EllipticArcBuilderEx.CreateCircle(
  new Coordinate2D(2, 4), 0.5, ArcOrientation.ArcClockwise, null);
var circle_poly = PolygonBuilderEx.CreatePolygon(PolylineBuilderEx.CreatePolyline(circle_seg));

//PolylineBuilderEx.CreatePolyline(cir, AttributeFlags.AllAttributes));
//Set symbolology, create and add element to layout
CIMStroke outline = SymbolFactory.Instance.ConstructStroke(
  ColorFactory.Instance.BlackRGB, 2.0, SimpleLineStyle.Dash);

CIMPolygonSymbol circleSym = SymbolFactory.Instance.ConstructPolygonSymbol(
  ColorFactory.Instance.RedRGB, SimpleFillStyle.Solid, outline);
SymbolFactory.Instance.ConstructPolygonSymbol(null,
  SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.RedRGB, 2));

var circleGraphic = GraphicFactory.Instance.CreateSimpleGraphic(circle_poly, circleSym);

//Make an element to add to GraphicsLayer or Layout
//var elemInfo = new ElementInfo() { Anchor = Anchor.CenterPoint };
//GraphicElement cirElm = ElementFactory.Instance.CreateGraphicElement(
//  container, circleGraphic, "New Circle", true, elemInfo);

//Must be on QueuedTask.Run(() => { ...

//Build geometry
Coordinate2D center = new Coordinate2D(4.5, 2.75);
var eabElp = new EllipticArcBuilderEx(center, 0, 1, 0.45, ArcOrientation.ArcClockwise);
var ellipse = eabElp.ToSegment();

var poly = PolygonBuilderEx.CreatePolygon(
  PolylineBuilderEx.CreatePolyline(ellipse, AttributeFlags.AllAttributes));

//Set symbolology, create and add element to layout
CIMTextSymbol sym = SymbolFactory.Instance.ConstructTextSymbol(
                      ColorFactory.Instance.BlueRGB, 10, "Arial", "Regular");
string text = "Ellipse, ellipse, ellipse";

GraphicElement ge = ElementFactory.Instance.CreateTextGraphicElement(
  container, TextType.PolygonParagraph, poly, sym, text, "New Ellipse Text", false);

//Must be on QueuedTask.Run(() => { ...

//PredefinedShape shapeType =
//              PredefinedShape.Circle | Cloud | Cross |Circle | Triangle | ... ;

//Build geometry
Coordinate2D ll = new Coordinate2D(4, 2.5);
Coordinate2D ur = new Coordinate2D(6, 4.5);
Envelope env = EnvelopeBuilderEx.CreateEnvelope(ll, ur);

var outline = SymbolFactory.Instance.ConstructStroke(
                ColorFactory.Instance.BlueRGB, 2);
var poly_sym = SymbolFactory.Instance.ConstructPolygonSymbol(
                 null, outline);

var ge = ElementFactory.Instance.CreatePredefinedShapeGraphicElement(
                       container, shapeType, env.Center, env.Width, env.Height, 
                        poly_sym, shapeType.ToString(), true);