10.
已知椭圆\(C\):\( \dfrac {x^{2}}{a^{2}}+ \dfrac {y^{2}}{b^{2}}=1(a > b > 0)\),过\(C\)上一点\((2 \sqrt {2}, \sqrt {2})\)的切线\(l\)的方程为\(x+2y-4 \sqrt {2}=0\).
\((1)\)求椭圆\(C\)的方程.
\((2)\)设过点\(M(0,1)\)且斜率不为\(0\)的直线交椭圆于\(A\),\(B\)两点,试问\(y\)轴上是否存在点\(P\),使得\( \overrightarrow{PM}=λ( \dfrac { \overrightarrow{PA}}{| \overrightarrow{PA}|}+ \dfrac { \overrightarrow{PB}}{| \overrightarrow{PB}|})\)?若存在,求出点\(P\)的坐标;若不存在说明理由.