实现效果：
知识运用：
Graphics类中的DrawPie方法
public void DrawPie (Pen pen,Rectangle rectangle, startAngle, float sweepAngle)
public void DrawPie (Pen pen, int x,int y int width ,int height, int startAngle ,int sweepAngle)
实现代码：
private void button1_Click(object sender, EventArgs e)
{
Graphics g = this.CreateGraphics();
Pen myPen = new Pen(Color.Black,2);
g.DrawPie(myPen,30,20,200,140,0,240);
}
原文：https://www.cnblogs.com/feiyucha/p/10257608.html