等周定理及其应用王三宝（湖北大冶师范学校４３５１００）在有某种性质的所有几何图形中，哪一个有最大面积（或最小周长）？特别地，在周长给定并满足某些条件的所有区域中，找出面积最大的区域，这类最值问题称之为等周问题，它在数学发展史上占有重要地位．下面谈谈等... Equal-cycle theorems and their applications Wang Sanbao (Daye Normal School, Hubei 435100) Which of the most geometrical figures of a certain nature has the largest area (or the smallest perimeter)? In particular, in all regions where the perimeter is given and satisfies certain conditions, the area with the largest area is found. This type of value problem is called the isoperimetric problem, which occupies an important position in the history of mathematical development. Let’s talk about etc...