初中数学八年级下册（648题）

---

知识点：第十八章　平行四边形

参考答案：证明：\(\because AF//BC\)

\(\therefore \angle AFE = \angle DBE\)

\(\because E\)是线段\(AD\)的中点

\(\therefore AE = DE\)

\(\because \angle AEF = \angle DEB\)

\(\therefore \Delta BDE\cong \Delta FAE(\text{AAS})\)

\(\therefore AF = BD\)

\(\because D\)是线段\(BC\)的中点

\(\therefore BD = CD\)

\(\therefore AF = CD\)

\(\because AF//CD\)

\(\therefore \)四边形\(ADCF\)是平行四边形

\(\because AB = AC\)

\(\therefore AD \bot BC\)

\(\therefore \angle ADC = 90^\circ \)

\(\therefore \)平行四边形\(ADCF\)为矩形