vocabulary
| 单词 | 中文 | 英文 |
| Perimeter | 周，周长 | the length of the outer edge of a shape |
| area | 面积 | the size of a flat surface calculated by multiplying its length by its width |
| length | 长，长度 | the measurement of something from end to end or along its longest side |
| width | 宽度；广度 | the distance across something from one side to the other |
| height | 高，高度 | the distance from the top to the bottom of something, or the quality of being tall |
| circumference | 圆周；周长；周线 | the line surrounding a circular space, or the length of this line |
| radius | 半径，半径长度 | a straight line joining the centre of a circle to its edge or the centre of a sphere to its surface |
| polygon | 多边形 | a flat shape with three or more straight sides |
| triangle | 三角形 | a flat shape with three straight sides |
| rectangle | 长方形；矩形 | a flat shape with four 90° angles and four sides, with opposite sides of equal length |
| side | 边 | an edge or border of something |