3.在平面直角坐標(biāo)系xOy中,對于點(diǎn)P和圖形G,給出如下定義:若圖形G上存在點(diǎn)T,使點(diǎn)P繞點(diǎn)T順時針旋轉(zhuǎn)60°后得到點(diǎn)Q,稱點(diǎn)Q為點(diǎn)P關(guān)于圖形G的“旋轉(zhuǎn)點(diǎn)”.特別地,若點(diǎn)T與點(diǎn)P重合,則點(diǎn)P也是點(diǎn)P關(guān)于圖形G的“旋轉(zhuǎn)點(diǎn)”.如圖1,點(diǎn)P(0,2).
(1)在點(diǎn)
,B(3,0),C(0,2)中,是點(diǎn)P關(guān)于y軸的“旋轉(zhuǎn)點(diǎn)”的是
;
(2)若⊙O上存在點(diǎn)P關(guān)于y軸的“旋轉(zhuǎn)點(diǎn)”,求⊙O的半徑r的取值范圍;
(3)如圖2,⊙O的半徑為2時,已知點(diǎn)D(t,0),E(t+1,0),以線段DE為邊在x軸上方作正方形DEFG.若正方形DEFG上存在點(diǎn)P關(guān)于⊙O的“旋轉(zhuǎn)點(diǎn)”,直接寫出符合題意的t的取值范圍.
?