25.平面直角坐標(biāo)系中,點(diǎn)B在x軸正半軸,點(diǎn)C在y軸正半軸,△ABC是等腰直角三角形,CA=CB,∠ACB=90°,AB交y軸負(fù)半軸于點(diǎn)D.
(1)如圖1,點(diǎn)C的坐標(biāo)是(0,4),點(diǎn)B的坐標(biāo)是(8,0),求點(diǎn)A的坐標(biāo);
(2)如圖2,AE⊥AB交x軸的負(fù)半軸于點(diǎn)E,連接CE,CF⊥CE交AB于F.
①求證:CE=CF;
②求證:點(diǎn)D是AF的中點(diǎn).