\((1)\)已知曲线\(y=x\ln x\)的一条切线为\(y=2x+b\),则实数\(b\)的值为_______.
\((2)\)若\(x,y\)满足约束条件\(\begin{cases}\begin{matrix}y\leqslant 2 \\ y\geqslant 2x-1\end{matrix} \\ x+y\geqslant -4\end{cases} \) ,则\(z=x-y\)的最大值为_________.
\((3)\)在四面体\(ABCD\)中,\(AB=CD=2\),\(AC=BD=AD=BC=\sqrt{2}\), 则该四面体的外接球的表面积为____________.
\((4)\)在\(∆ABC \)中,内角\(A,B,C\)的对边分别为\(a,b,c\),且\(a > b,a > c\).\(\Delta ABC\)的外接圆半径为\(1\),\(a=\sqrt{3}.\)若边\(BC\)上一点\(D\)满足\(BD=2DC\),且\(\angle BAD={{90}^{\circ }}\),则\(\Delta ABC\)的面积为__________.