27.已知?jiǎng)狱c(diǎn)A從原點(diǎn)O出發(fā)沿?cái)?shù)軸向左運(yùn)動(dòng),同時(shí)動(dòng)點(diǎn)B也從原點(diǎn)出發(fā)沿?cái)?shù)軸向右運(yùn)動(dòng),動(dòng)點(diǎn)A的速度為每秒1個(gè)單位長(zhǎng)度,動(dòng)點(diǎn)B的速度為每秒2個(gè)單位長(zhǎng)度,5秒后動(dòng)點(diǎn)B調(diào)轉(zhuǎn)方向向左運(yùn)動(dòng),A、B兩點(diǎn)的速度仍保持不變,則
秒后A、B、O三點(diǎn)中一點(diǎn)到另兩個(gè)點(diǎn)的距離相等.