//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);