初中数学八年级下册（648题）

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知识点：复习

参考答案：证明：

\(\because AE \bot BC\)，\(AF \bot CD\)，

\(\therefore \angle AEB = \angle AFD\)＝90°，

\(\because \)四边形\(ABCD\)是菱形，

\(\therefore AB = AD\)，\(\angle B = \angle D\)，

在\(\Delta ABE\)和\(\Delta ADF\)中，

\(\left\{ {\begin{array}{*{20}{l}} {\angle AEB = \angle AFD} \\ {\angle B = \angle D} \\ {AB = AD} \end{array}} \right.\)，

\(\therefore \Delta ABE \cong \Delta ADF(AAS)\)，

\(\therefore BE = DF\)。