22.如圖,△ABC是邊長(zhǎng)為6cm的等邊三角形,動(dòng)點(diǎn)P、Q同時(shí)從A、B兩點(diǎn)出發(fā),分別沿AB、BC方向勻速移動(dòng).
(1)當(dāng)點(diǎn)P的運(yùn)動(dòng)速度是1cm/s,點(diǎn)Q的運(yùn)動(dòng)速度是2cm/s,當(dāng)Q到達(dá)點(diǎn)C時(shí),P、Q兩點(diǎn)都停止運(yùn)動(dòng),設(shè)運(yùn)動(dòng)時(shí)間為t(s),當(dāng)t=2時(shí),判斷△BPQ的形狀,并說(shuō)明理由;
(2)當(dāng)它們的速度都是1cm/s,當(dāng)點(diǎn)P到達(dá)點(diǎn)B時(shí),P、Q兩點(diǎn)停止運(yùn)動(dòng),設(shè)點(diǎn)P的運(yùn)動(dòng)時(shí)間為t(s),則當(dāng)t為何值時(shí),△PBQ是直角三角形?