ArcGIS Pro 2.7 API Reference Guide
CreateEllipticArcSegment(Coordinate2D,Double,esriArcOrientation,SpatialReference) Method
Example 

ArcGIS.Core.Geometry Namespace > EllipticArcBuilder Class > CreateEllipticArcSegment Method : CreateEllipticArcSegment(Coordinate2D,Double,esriArcOrientation,SpatialReference) Method
The center of the circle.
The radius of the circle.
The ellipse orientation, clockwise or counterclockwise.
(Optional) The SpatialReference of the ellipse. The default value is null.
Convenience method to create a new instance of the EllipticArcSegment class. The new instance will build a circle from a center point and radius.
Syntax
Public Overloads Shared Function CreateEllipticArcSegment( _
   ByVal centerPt As Coordinate2D, _
   ByVal radius As Double, _
   ByVal orientation As esriArcOrientation, _
   Optional ByVal spatialReference As SpatialReference _
) As EllipticArcSegment

Parameters

centerPt
The center of the circle.
radius
The radius of the circle.
orientation
The ellipse orientation, clockwise or counterclockwise.
spatialReference
(Optional) The SpatialReference of the ellipse. The default value is null.

Return Value

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