平行四边形(包括矩形、正方形、菱形)的两组对边、对角和对角线都具有某些相同性质,所以在添辅助线方法上也有共同之处,目的都是造就线段的平行、垂直,构成三角形的全等、相似,把平行四边形问题转化成常见的三角形、正方形等问题处理,其常用方法有下列几种.举例简解如下. The two sets of opposite sides, diagonals and diagonals of a parallelogram (including a rectangle, a square, a diamond) have some of the same properties, so there are also commonalities in the method of adding aids, with the aim of creating parallel, , Constitute the triangle congruent, similar to the parallelogram into common problems such as triangles, squares and other issues, the commonly used methods are the following kinds.