The function returns a piecewise approximation of a geodesic ellipse (or geodesic circle, if SemiAxis1Length = SemiAxis2Length). Constructs a geodesic ellipse centered on the specified point. If this method is used to generate a polygon or a polyline, the result may have more than one part, depending on the size of the sector and its position relative to the horizon of the coordinate system. When the method generates a polyline or a multipoint, the result vertices lie on the boundary of the ellipse. When a polygon is generated, the interior of the polygon is the interior of the sector, however the boundary of the polygon may contain segments from the spatial reference horizon, or from the GCS extent.

public Geometry GeodesicSector( 
   GeodesicSectorParameter parameter,
   SpatialReference spatialReference
)

Public Function GeodesicSector( _
   ByVal parameter As GeodesicSectorParameter, _
   ByVal spatialReference As SpatialReference _
) As Geometry

GeodesicSectorParameter param = new GeodesicSectorParameter();
param.ArcVertexCount = 50;
param.AxisDirection = Math.PI / 4;
param.Center = new Coordinate2D(0, 0);
param.LinearUnit = LinearUnit.Meters;
param.OutGeometryType = GeometryType.Polygon;
param.RadiusVertexCount = 10;
param.SectorAngle = 5 * Math.PI / 3;
param.SemiAxis1Length = 100000;
param.SemiAxis2Length = 20000;
param.StartDirection = 11 * Math.PI / 6;

Geometry geometry = GeometryEngine.Instance.GeodesicSector(param, SpatialReferences.WGS84);
// geometry.IsEmpty = false

Polygon polygon = geometry as Polygon;
// polygon.PointCount = 68
// polygon.PartCount = 1