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#c89f097f-29aa-46c2-868b-2e4ea31bf6dc中等解答题直线与圆的位置关系直线与圆+圆锥曲线

27. 已知圆C1:x2+y22x2y+1=0C_{1}:x^{2}+y^{2}-2x-2y+1=0,圆C2:(x4)2+(y5)2=r2(r>0)C_{2}:(x-4)^{2}+(y-5)^{2}=r^{2}(r>0)
(1)若圆C1C_{1}与圆C2C_{2}外切,求rr的值;
(2)若圆C1C_{1}与圆C2C_{2}有两个交点,求rr的取值范围.