28.在平面直角坐標(biāo)系xOy中,已知點(diǎn)M不與原點(diǎn)重合.對(duì)于點(diǎn)P給出如下定義:點(diǎn)P關(guān)于點(diǎn)M的對(duì)稱點(diǎn)為P′,點(diǎn)P′關(guān)于直線OM的對(duì)稱點(diǎn)為Q,稱點(diǎn)Q是點(diǎn)P關(guān)于點(diǎn)M的“轉(zhuǎn)稱點(diǎn)”.
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(1)如圖,已知點(diǎn)M(t,0),P(t+1,1),點(diǎn)Q是點(diǎn)P關(guān)于點(diǎn)M的“轉(zhuǎn)稱點(diǎn)”.
①當(dāng)t=2時(shí),在圖中畫出點(diǎn)Q的位置,并直接寫出點(diǎn)Q的坐標(biāo);
②PQ的長(zhǎng)度是否與t有關(guān)?若無關(guān),求PQ的長(zhǎng);若有關(guān),說明理由;
(2)已知點(diǎn)A(3,4),△ABC是邊長(zhǎng)為2的等邊三角形(點(diǎn)A,B,C按逆時(shí)針方向排列),點(diǎn)N是點(diǎn)B關(guān)于點(diǎn)C的“轉(zhuǎn)稱點(diǎn)”,在△ABC繞點(diǎn)A旋轉(zhuǎn)的過程中,當(dāng)BN最大時(shí),直接寫出此時(shí)OB的長(zhǎng).