平行四边形这部分,定理比较多,同学们学习时,思路容易混乱。那么,怎样才能学好这部分内容呢? 一、弄清定理之间的关系。平行四边形这部分的定理包括平行四边形、矩形、菱形和正方形的性质定理与判定定理,而性质定理和判定定理往往是一对互为逆定理,同学们学习时可把性质和判定对照 In this part of the parallelogram, there are many theorems. When the students are learning, their ideas are easily confused. So, how can we learn this part of the content? First, clarify the relationship between the theorems. The theorem of this part of the parallelogram consists of the properties theorem and decision theorem of parallelograms, rectangles, rhombuses and squares. The property theorem and the theorem of judgment are often a pair of mutually opposite theorems. Students can compare the properties and judgments when learning.