10.
\((1)\)以点\(M(2,0)\)、\(N(0,4)\)为直径的圆的标准方程为________.
\((2)\)在等差数列\(\{a_{n}\}\)中,\(a_{n} > 0\),\({{a}_{7}}=\dfrac{1}{2}{{a}_{4}}+4\),\(S_{n}\)为数列\(\{a_{n}\}\)的前\(n\)项和,\(S_{19}=\)________.
\((3)\)已知点\(P(a,b)\)在函数\(y=\dfrac{{{e}^{2}}}{x}\)上,且\(a > 1\),\(b > 1\),则\(a^{\ln b}\)的最大值为________.
\((4)\)已知双曲线\(C_{2}\)与椭圆\(C_{1}\):\(\dfrac{{{x}^{2}}}{4}+\dfrac{{{y}^{2}}}{3}=1\)具有相同的焦点,则两条曲线相交四个交点形成四边形面积最大时双曲线\(C_{2}\)的离心率为________.