public MapPoint this[ 
   int index
]; {get;}

// build a polygon      
List<MapPoint> pts = new List<MapPoint>();
pts.Add(MapPointBuilder.CreateMapPoint(1.0, 1.0));
pts.Add(MapPointBuilder.CreateMapPoint(1.0, 2.0));
pts.Add(MapPointBuilder.CreateMapPoint(2.0, 2.0));
pts.Add(MapPointBuilder.CreateMapPoint(2.0, 1.0));

Polygon poly = PolygonBuilder.CreatePolygon(pts);

// test if an inner point is contained
MapPoint innerPt = MapPointBuilder.CreateMapPoint(1.5, 1.5);
bool contains = GeometryEngine.Instance.Contains(poly, innerPt);   // contains = true

// test a point on a boundary
contains = GeometryEngine.Instance.Contains(poly, poly.Points[0]);     // contains = false

// test an interior line
MapPoint innerPt2 = MapPointBuilder.CreateMapPoint(1.25, 1.75);
List<MapPoint> innerLinePts = new List<MapPoint>();
innerLinePts.Add(innerPt);
innerLinePts.Add(innerPt2);

// test an inner polyline
Polyline polyline = PolylineBuilder.CreatePolyline(innerLinePts);
contains = GeometryEngine.Instance.Contains(poly, polyline);   // contains = true

// test a line that crosses the boundary
MapPoint outerPt = MapPointBuilder.CreateMapPoint(3, 1.5);
List<MapPoint> crossingLinePts = new List<MapPoint>();
crossingLinePts.Add(innerPt);
crossingLinePts.Add(outerPt);

polyline = PolylineBuilder.CreatePolyline(crossingLinePts);
contains = GeometryEngine.Instance.Contains(poly, polyline);     // contains = false

// test a polygon in polygon
Envelope env = EnvelopeBuilder.CreateEnvelope(innerPt, innerPt2);
contains = GeometryEngine.Instance.Contains(poly, env);      // contains = true