centroid center of volume

例句：

1. 1.The centroid of the circle is at its center.
   圆的重心在其中心。
2. 2.The team's centroid is in the center of the field.
   队伍的中心在场地中央。
3. 3.The centroid of the triangle is the point where all three sides intersect.
   三角形的重心是三条边交点的一点。