《中学生数学》(初中)2011年第7期(下)登载的“等腰梯形的一个性质及推广”一文,介绍了等腰梯形的一个颇为有趣的性质,并作了相应的推广,阅后很受启发,其证明应用了平面几何中的重要定理——托勒密定理,简洁、巧妙,毋庸置疑,但初中生对此定理较为陌生,一时难于理解,只能望 “Secondary School Mathematics” (junior high school) 2011 seventh period (below) published “a isosceles trapezoid and a promotion of nature,” a text, introduced a isosceles trapezoid a rather interesting nature, and made the corresponding promotion , After reading very inspired, which proves that the application of the important theorem in plane geometry - Ptolemy theorem, concise, clever, no doubt, but the junior high school students more unfamiliar with this theorem, sometimes difficult to understand, can only hope