ArcGIS Pro 2.7 API Reference Guide
EllipticArcBuilder Constructor(Coordinate2D,Double,esriArcOrientation,SpatialReference)
Example 

ArcGIS.Core.Geometry Namespace > EllipticArcBuilder Class > EllipticArcBuilder Constructor : EllipticArcBuilder Constructor(Coordinate2D,Double,esriArcOrientation,SpatialReference)
The center of the circle.
The radius of the circle.
The orientation of the arc, clockwise or counterclockwise.
(Optional) The spatial reference of the arc. The default value is null.
Builds a new instance of the EllipticArcBuilder class. The new instance will be a circle from a center point and radius. This method must be called on the MCT. Use QueuedTask.Run.
Syntax

Parameters

centerPt
The center of the circle.
radius
The radius of the circle.
orientation
The orientation of the arc, clockwise or counterclockwise.
spatialReference
(Optional) The spatial reference of the arc. The default value is null.
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
Example
// Construct a circle with center at (-1,-1), radius = 2, and oriented clockwise.
// Use a builder convenience method or use a builder constructor.

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

// Builder convenience methods don't need to run on the MCT.
EllipticArcSegment circle = EllipticArcBuilder.CreateEllipticArcSegment(centerPtCoord, 2, esriArcOrientation.esriArcClockwise);
// 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

// Builder constructors need to run on the MCT.
ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
{
  using (EllipticArcBuilder builder = new EllipticArcBuilder(centerPtCoord, 2, esriArcOrientation.esriArcClockwise))
  {
    // do something with the builder

    EllipticArcSegment otherCircle = builder.ToSegment();
  }
});
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

EllipticArcBuilder Class
EllipticArcBuilder Members
Overload List