26.已知等邊△ABC的邊長(zhǎng)為4cm,點(diǎn)P,Q分別從B,C兩點(diǎn)同時(shí)出發(fā),其中點(diǎn)P沿BC向終點(diǎn)C運(yùn)動(dòng),速度為1cm/s;點(diǎn)Q沿CA,AB向終點(diǎn)B運(yùn)動(dòng),速度為2cm/s,設(shè)它們運(yùn)動(dòng)的時(shí)間為x(s).
(1)如圖1,若PQ∥AB,則x的值為
(s).
(2)如圖2,若PQ⊥AC,求x的值.
(3)如圖3,當(dāng)點(diǎn)Q在AB上運(yùn)動(dòng)時(shí),PQ與△ABC的高AD交于點(diǎn)O,OQ與OP是否總是相等?請(qǐng)說明理由.