證明：?$(1)$?在?$ \triangle AOB $?和?$ \triangle COD $?中
?$\begin {cases}{∠A = ∠C}\\{OA = OC}\\{∠AOB = ∠COD}\end {cases}$?
∴?$\triangle AOB ≌ \triangle COD (AS A)，$?∴?$ OB = OD $?
?$(2)$?∵?$OB = OD，$?∴點(diǎn)?$ O $?在?$ BD $?的垂直平分線上
又∵?$BE = DE，$?∴點(diǎn)?$ E $?在?$ BD $?的垂直平分線上
∴?$ OE $?垂直平分?$ BD $?
