5.
在直角坐标系\(xoy\)中,曲线\(C\)的参数方程为\({ }\!\!\{\!\!{ }\begin{matrix} x=\sin \alpha +\cos \alpha \\ y=\sin \alpha -\cos \alpha \\\end{matrix}{ }(\alpha \)为参数\()\).
\((\)Ⅰ\()\)求曲线\(C\)的普通方程;
\((\)Ⅱ\()\)在以\(o\)为极点,\(x\)轴的非负半轴为极轴的极坐标系中,直线\(l\)方程为\(\sqrt{2}\rho {\sin }\left( \dfrac{{ }\!\!\pi\!\!{ }}{{4}}-\theta \right)+\dfrac{{1}}{{2}}=0\),已知直线\(l\)与曲线\(C\)相交于\(A\)、\(B\)两点,求\(\left| AB \right|\).