证明等边三角形的方法比较多.在具体的证明过程中,应根据已知条件灵活选择证明方法.一、证明三角相等例1如图1,在△ABC中,D是AB上任意一点.DE⊥AC于点E,ED的延长线与CB的延长线交于点F.若BD=BF,∠ABC=∠A,试判断△ABC的形状,并说明理由.解:△ABC是等边三角形,理由如下: Proof of equilateral triangles more.In the specific proof of the process, should be based on the known conditions of flexible choice of proof methods. First, prove the triangular equivalent Example 1 In △ ABC, D is any point on AB .DE ⊥ AC at the point E, ED extension line and extension of CB intersection at point F. If BD = BF, ∠ ABC = ∠ A, try to determine the shape of △ ABC and explain the reason. △ ABC is equilateral triangle For the following reasons: