《中学生数学》2007年第10期刊登了李金珠、崔国莲两位老师的文章《等边三角形的一个定值》,读罢颇受启发.笔者研究发现等腰梯形中也存在一个定值,觉得很有趣,而且可以进一步探究,且探究过程也很有趣,在此提出与各位同仁切磋. The mathematics of middle school students published the article “Limited Triangular Equilateral Triangles” by Li Jinzhu and Cui Guolian in the 10th issue of 2007. It was inspired by the author’s research. The author found that there is also a fixed value in the isosceles trapezoid. It is interesting and can be further explored, and the inquiry process is also very interesting. Here, I would like to discuss with my colleagues.