$证明：(1)\because CE∥AB，$
$\therefore \angle E=\angle EAB，\angle B=\angle ECB，$
$\therefore \triangle CED∽\triangle BAD，$
$\therefore \frac {CE}{AB}=\frac {CD}{BD}，$
$\because \angle E=\angle EAB，\angle EAB=\angle CAD，$
$\therefore \angle E=\angle CAD，$
$\therefore CE=CA，$
$\therefore \frac {AB}{AC}=\frac {BD}{CD}.$
（更多请点击查看作业精灵详解）
