closed polygon

例句：

1. 1.This closed polygon is used to represent a complex shape in CAD software.
   这个闭合多边形在CAD软件中用来表示一个复杂的形状。
2. 2. The engineer drew a closed polygon to enclose the area.
   工程师画了一个闭合多边形来包围那个区域。
3. 3. The mathematician used a closed polygon to solve the problem.
   数学家使用一个闭合多边形来解决那个问题。