《中小学数学》(初中版)2014年第11期刊登了李金芳的《这样举例比较好》,2015年第7—8期刊登了吴维岗、徐金豹的《这个结论正确吗》.两篇文章都对2014年第4期刊登的黄世文的《在三角形中裁出一个面积最大的正方形》一文中存在的错误进行了纠正.遗憾的是,黄老师文中还有一个更为隐蔽错误,两篇文章均未能发现.本文将对这一错误进行剖析. “Primary and Secondary Mathematics” (Junior High School Edition) published in 2014 the 11th issue of Li Jinfang’s “This example is better.” In the 7th to 8th issue of 2015, Wu Weigang and Xu Jinbao published “Is this conclusion correct?” Both articles are correct. The mistakes in Huang Shiwen’s article “Cutting Out the Largest Square in Triangles” published in the 4th issue of 2014 were corrected. Unfortunately, there is a more subtle mistake in Huang’s writing, and neither article is correct. Can be found. This article will analyze this error.