4.
如图,直线\(OC\),\(BC\)的函数关系式分别是\(y\)\({\,\!}_{1}\)\(=\)\(\dfrac{1}{2}\)\(x\)和\(y\)\({\,\!}_{2}\)\(=\)\(-\)\(x+\)\(6\),两直线的交点为\(C\).
\((1)\)求点\(C\)的坐标,并直接写出\(y\)\({\,\!}_{1} > \)\(y\)\({\,\!}_{2}\)时\(x\)的范围;
\((2)\)在直线\(y\)\({\,\!}_{1}\)上找点\(D\),使\(\triangle \)\(DCB\)的面积是\(\triangle \)\(COB\)的一半,求点\(D\)的坐标;
\((3)\)点\(M\)\((\)\(t\),\(0)\)是\(x\)轴上的任意一点,过点\(M\)作直线\(l\)\(⊥x\)轴,分别交直线\(y\)\({\,\!}_{1}\)、\(y\)\({\,\!}_{2}\)于点\(E\)、\(F\),当\(E\)、\(F\)两点间的距离不超过\(4\)时,求\(t\)的取值范围.