[知识要点]1 除具有平行四边形的性质外,矩形还具有:(1) 　　　　;(2) 　　　　;(3) 　　　　 菱形还具有的性质: (1) 　　　　;(2) 　　　　;(3) 　　　　 正方形除具有平行四边形、矩形、菱形的性质外,还具有:(1) 　　　　;(2) 　　　　 2 矩形的判定方法: (1) 　　　　; [Knowledge points] 1 In addition to the nature of parallelograms, rectangles also have: (1) (2) (3) Diamonds also have properties: (1) (2) (3) Squares have a parallelogram In addition to the nature of rectangles and diamonds, it also has: (1) (2) Rectangular determination methods: (1);