25.如圖,直線AM⊥AN,AB平分∠MAN,過(guò)點(diǎn)B作BC⊥BA交AN于點(diǎn)C,動(dòng)點(diǎn)E、D同時(shí)從A點(diǎn)出發(fā),其中動(dòng)點(diǎn)E以2cm/s的速度沿射線AN向點(diǎn)C運(yùn)動(dòng),動(dòng)點(diǎn)D以1cm/s的速度沿射線AM上運(yùn)動(dòng),當(dāng)點(diǎn)E到達(dá)點(diǎn)C時(shí)停止運(yùn)動(dòng),已知AC=6cm,設(shè)動(dòng)點(diǎn)D,E的運(yùn)動(dòng)時(shí)間為t(s).
(1)求證:AB=CB;
(2)若S
△ABD:S
△BEC=2:3,求t的值;
(3)在點(diǎn)D,E運(yùn)動(dòng)過(guò)程中,是否存在某時(shí)刻t,使得DB⊥BE?若存在,求出t的值;若不存在,請(qǐng)說(shuō)明理由.