2.
已知\(P\)是焦距为\(4\sqrt{2}\)的双曲线\(C\):\(\dfrac{{{x}^{2}}}{{{a}^{2}}}-\dfrac{{{y}^{2}}}{{{b}^{2}}}=1\left( a > 0,b > 0 \right)\)上一点,过\(P\)的直线与双曲线\(C\)的两条渐近线分别交于点\({{P}_{1}}\),\({{P}_{2}}\),且\(3\overrightarrow{OP}=\overrightarrow{O{{P}_{1}}}+2\overrightarrow{O{{P}_{2}}}\),\(O\)为坐标原点.
\((\)Ⅰ\()\)设\({{P}_{1}}\left( {{x}_{1}},{{y}_{1}} \right)\),\({{P}_{2}}\left( {{x}_{2}},{{y}_{2}} \right)\),证明:\({{x}_{1}}{{x}_{2}}-{{y}_{1}}{{y}_{2}}=9\);
\((\)Ⅱ\()\)试求当\(\Delta O{{P}_{1}}{{P}_{2}}\)面积取得最大值时双曲线的方程.