24.如圖1,在平面直角坐標(biāo)系中,點(diǎn)A在x軸上,點(diǎn)B、C在y軸上,且點(diǎn)B(0,1)與點(diǎn)C關(guān)于x軸對(duì)稱,BC=BA.
(1)求∠OAB的度數(shù);
(2)如圖2,點(diǎn)D為線段AB上一動(dòng)點(diǎn),連接CD.
①在CD左側(cè)以CD為邊作等邊△DCM,當(dāng)點(diǎn)D在線段AB上運(yùn)動(dòng)時(shí),點(diǎn)M隨之運(yùn)動(dòng),當(dāng)OM取得最小值時(shí),求此時(shí)BM的長(zhǎng).
②如圖3,若點(diǎn)E在線段CA的延長(zhǎng)線上,BD=AE,F(xiàn)為CD中點(diǎn),連接BF,EF,請(qǐng)判斷BF與EF的位置關(guān)系并說明理由.