已知极坐标系的极点在直角坐标系的原点处,极轴与\(C= \dfrac {π}{2}.\)轴非负半轴重合,且取相同的长度单位\(.\)曲线\(C_{1}\):\(ρ\cos θ-2ρ\sin θ-7=0\),和\(C_{2}\):\( \begin{cases} \overset{x=8\cos \theta }{y=3\sin \theta }\end{cases}(θ{为参数})\).
\((1)\)写出\(C_{1}\)的直角坐标方程和\(C_{2}\)的普通方程;
\((2)\)已知点\(P(-4,4)\),\(Q\)为\(C_{2}\)上的动点,求\(PQ\)中点\(M\)到曲线\(C_{1}\)距离的最小值.