8.
.如图,在平面直角坐标系\(xOy\)中,已知以\(M\)为圆心的圆\(M\)\(:\)\(x\)\({\,\!}^{2}\)\(+y\)\({\,\!}^{2}\)\(-\)\(12\)\(x-\)\(14\)\(y+\)\(60\)\(=\)\(0\)及其上一点\(A\)\((2,4)\).
\((1)\)设圆\(N\)与\(x\)轴相切,与圆\(M\)外切,且圆心\(N\)在直线\(x=\)\(6\)上,求圆\(N\)的标准方程\(;\)
\((2)\)设平行于\(OA\)的直线\(l\)与圆\(M\)相交于\(B\),\(C\)两点,且\(BC=OA\),求直线\(l\)的方程\(;\)
\((3)\)设点\(T\)\((\)\(t\),\(0)\)满足:存在圆\(M\)上的两点\(P\)和\(Q\),使得\( \overset{→}{TA}+ \overset{→}{TP}= \overset{→}{TQ} \),求实数\(t\)的取值范围.