public EllipticArcBuilderEx( 
   Coordinate2D centerPt,
   double rotationAngle,
   double semiMajorAxis,
   double minorMajorRatio,
   ArcOrientation orientation,
   SpatialReference spatialReference
)

// Construct an ellipse centered at (1, 2) with rotationAngle = -pi/6,  
// semiMajorAxis = 5, minorMajorRatio = 0.2, oriented clockwise.
// Use a builderEx convenience method or use a builderEx constructor.

Coordinate2D centerPt = new Coordinate2D(1, 2);

// BuilderEx convenience methods don't need to run on the MCT.
EllipticArcSegment ellipse = EllipticArcBuilderEx.CreateEllipse(centerPt, -1 * Math.PI / 6, 5, 0.2, ArcOrientation.ArcClockwise);

// This EllipticArcBuilderEx constructor doesn't need to run on the MCT.
EllipticArcBuilderEx builder = new EllipticArcBuilderEx(centerPt, -1 * Math.PI / 6, 5, 0.2, ArcOrientation.ArcClockwise);
EllipticArcSegment anotherEllipse = builder.ToSegment();

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

//Build geometry
Coordinate2D center = new Coordinate2D(4.5, 4);
var eabCir = new EllipticArcBuilderEx(center, 0.5, ArcOrientation.ArcClockwise);
var cir = eabCir.ToSegment();

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

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

GraphicElement cirTxtElm = ElementFactory.Instance.CreateTextGraphicElement(
  container, TextType.CircleParagraph, poly, sym, text, "New Circle Text", false);

//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);