选择菱形的判定方法时,应先注意前提条件,是一般四边形还是平行四边形,或其他的特殊平行四边形.然后从边、角、对角线的特征方面去判定.具体方法如下:此外,由两个等边三角形组合成的四边形也是菱形.一平行四边形+一组邻边相等→菱形例1如图1,在△ABC中,D,E分别是AB,AC的中点.过点E作EF∥AB,交BC于点F.(1)求证:四边形DBFE是平行四边形.(2)当△ABC满足什么条件时,四边形DBFE是菱形?为什么?简析:(1)根据三角形的中位线的性质 When choosing the decision method of rhombus, you should pay attention to the precondition, whether it is general quadrilateral or parallelogram, or other special parallelogram, and then judge from the features of edge, angle and diagonal as follows: In addition, A combination of equilateral triangles is also a diamond quadrilateral.A parallelogram + a group of adjacent edges equal to diamond example 1 shown in Figure 1, △ ABC, D, E, respectively, AB, AC midpoint over E as EF ∥ AB, pay BC at point F. (1) Confirmation: Quadrilateral DBFE is a parallelogram. (2) When △ ABC meet the conditions, the quadrilateral DBFE is diamond? Why? Analysis: (1) According to the triangular median line The nature of