10.
已知圆\(C\)的圆心在坐标原点\(O\),且与直线\(l_{1}\):\(x-y-2 \sqrt {2}=0\)相切.
\((1)\)求直线\(l_{2}\):\(4x-3y+5=0\)被圆\(C\)所截得的弦\(AB\)的长;
\((2)\)若与直线\(l_{1}\)垂直的直线与圆\(C\)交于不同的两点\(P\),\(Q\),且以\(PQ\)为直径的圆过原点,求直线的纵截距;
\((3)\)过点\(G(1,3)\)作两条与圆\(C\)相切的直线,切点分别为\(M\),\(N\),求直线\(MN\)的方程.