private static double AreaPolygon(PointF[] points)
        {
            double s = 0;
            for (int i = 0; i < points.Length - 1; i++)
            {
                 s += (points[i + 1].X - points[i].X) * (points[i + 1].Y + points[i].Y) / 2;
            }
            return Math.Abs(s);
        }

        public static double GeoAreaPolygon(PointF[] points)
        {
            double Lekv = 40075700;
            double Lmer = 40008550; //40 008,6

            ArrayList lat = new ArrayList();
            ArrayList lon = new ArrayList();
            foreach (PointF point in points)
            {
                lat.Add(point.X);
                lon.Add(point.Y);
            }
            ArrayList nds = new ArrayList();
            for (int i = 0; i < points.Length; i++)
            {
                double mlat = (float)lat[i] * Lekv / 360;
                double radlat = (float)lat[i] / (180 / Math.PI);
                double mlon = (float)lon[i] * Math.Cos(radlat) * Lmer / 360;
                nds.Add(new PointF((float)mlat, (float)mlon));
            }
            PointF[] arrPoints = new PointF[points.Length];
            for (int i = 0; i < nds.Count; i++)
            {
                arrPoints[i] = (PointF)nds[i];
            }
            return AreaPolygon(arrPoints);
        }