ArcGIS Pro 2.7 API Reference Guide
Buffer(Geometry,Double) Method
Example 

ArcGIS.Core.Geometry Namespace > IGeometryEngine Interface > Buffer Method : Buffer(Geometry,Double) Method
Specifies the input geometry.
The distance (in the unit of the geometry's spatial reference) to buffer the geometry.
Creates a buffer polygon at the specified distance around the given geometry.
Syntax
Overloads Function Buffer( _
   ByVal geometry As Geometry, _
   ByVal distance As Double _
) As Geometry

Parameters

geometry
Specifies the input geometry.
distance
The distance (in the unit of the geometry's spatial reference) to buffer the geometry.

Return Value

The polygon that represents the buffered area.
Exceptions
ExceptionDescription
Geometry is null or empty.
The method is not implemented for GeometryBag.
The buffer distance must be a valid floating point number.
Remarks
If the buffer distance is zero and the input geometry is a polygon or an envelope, then a polygon created from the input geometry is returned.

If the distance is less than or equal to zero and the input geometry is not a polygon or an envelope, then an empty polygon is returned.

GeometryEngine Buffer

Example
// buffer a point
MapPoint pt = MapPointBuilder.CreateMapPoint(1.0, 1.0, SpatialReferences.WGS84);
Geometry ptBuffer = GeometryEngine.Instance.Buffer(pt, 5.0);
Polygon buffer = ptBuffer as Polygon;
// create the circular arc
MapPoint fromPt = MapPointBuilder.CreateMapPoint(2, 1);
MapPoint toPt = MapPointBuilder.CreateMapPoint(1, 2);
Coordinate2D interiorPt = new Coordinate2D(1 + Math.Sqrt(2) / 2, 1 + Math.Sqrt(2) / 2);

EllipticArcSegment circularArc = EllipticArcBuilder.CreateEllipticArcSegment(fromPt, toPt, interiorPt);

// buffer the arc
Polyline polyline = PolylineBuilder.CreatePolyline(circularArc);
Geometry lineBuffer = GeometryEngine.Instance.Buffer(polyline, 10);
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

IGeometryEngine Interface
IGeometryEngine Members
Overload List