证明:在$\triangle AOB$与$\triangle COD$中,
$\begin{cases}\angle A = \angle C \\OA = OC \\\angle AOB = \angle COD\end{cases}$
$\therefore \triangle AOB\cong\triangle COD(ASA),$
$\therefore OB = OD,$
$\therefore$点$O$在线段$BD$的垂直平分线上.
$\because BE = DE,$
$\therefore$点$E$在线段$BD$的垂直平分线上,
$\therefore OE$垂直平分$BD.$