目前知道有两种方法：画多边形、GraphicsPath。但是用画多边形的方式画三角形不太好。老画不正的，截图放大就明显了。
1 Point point1 = new Point(0, 0);
2 Point point2 = new Point(11, 0);
3 Point point3 = new Point(5, 8);
4 Point[] pntArr = {point1, point2, point3};
5
6 e.Graphics.FillPolygon(Brushes.Red, pntArr);
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2 Point point2 = new Point(11, 0);
3 Point point3 = new Point(5, 8);
4 Point[] pntArr = {point1, point2, point3};
5
6 e.Graphics.FillPolygon(Brushes.Red, pntArr);
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