5.
已知极点为直角坐标系的原点,极轴为\(x\)轴正半轴且单位长度相同的极坐标系中曲线\(C_{1}\):\(ρ=1\),\(C_{2}: \begin{cases} x= \dfrac { \sqrt {2}}{2}t-1 \\ y= \dfrac { \sqrt {2}}{2}t+1\end{cases}(t\)为参数\()\).
\((\)Ⅰ\()\)求曲线\(C_{1}\)上的点到曲线\(C_{2}\)距离的最小值;
\((\)Ⅱ\()\)若把\(C_{1}\)上各点的横坐标都扩大为原来的\(2\)倍,纵坐标扩大为原来的\( \sqrt {3}\)倍,得到曲线\(C_{1}^{′}.\)设\(P(-1,1)\),曲线\(C_{2}\)与\(C_{1}^{′}\)交于\(A\),\(B\)两点,求\(|PA|+|PB|\).