1. In geometry, an isoperimeter is a curve of equal perimeter with respect to some geometrical quantity.(在几何学中,等周线是相对某些几何量具有相等周长的曲线。)
2. An isoperimeter is a curve that connects two points in such a way that its length is minimal among all curves that have the same enclosed area.(等周线是一条将两个点连接起来的曲线,其长度在所有具有相同封闭面积的曲线中是最小的。)