5.
以直角坐标系\(xOy\)的原点为极点,\(x\)轴的非负半轴为极轴建立极坐标系,且两坐标系相同的长度单位\(.\)已知点\(N\)的极坐标为\((\sqrt{2},\dfrac{\pi }{4})\),\(M\)是曲线\({{C}_{1}}:\rho =1\)上任意一点,点\(G\)满足\(\overrightarrow{OG}=\overrightarrow{OM}+\overrightarrow{ON}\),设点\(G\)的轨迹为曲线\({{C}_{2}}\).
\((1)\)求曲线\({{C}_{2}}\)的直角坐标方程;
\((2)\)若过点\(P(2,0)\)的直线\(l\)的参数方程为\(\begin{cases} x=2-\dfrac{1}{2}t \\ y=\dfrac{\sqrt{3}}{2}t \\ \end{cases}(t\)为参数\()\),且直线\(l\)与曲线\({{C}_{2}}\)交于\(A,B\)两点,求\(\dfrac{1}{|PA|}+\dfrac{1}{|PB|}\)的值.