pentagonum

例句：

1. 1.The pentagon is a geometric shape with five sides.
   五边形是一种具有五个边的几何形状。
2. 2. The pentagram is often used in divination and magic.
   五角星通常用于占卜和魔法。
3. 3.The pentagon is a popular design element in architecture.
   五角星是建筑中常见的设计元素。