10.
\((1)\)数列\(\{{a}_{n}\} \)满足\({a}_{n+1}+(-1{)}^{n}{a}_{n}=2n-1 \),则\(\{{a}_{n}\} \)的前\(12\)项和为 .
\((2)\)如图,四边形\(ABCD\)中,\(B=C=120^{\circ}\),\(AB=4\),\(BC=CD=2\),则该四边形的面积等于__________.
\((3)\)数列\(\{{a}_{n}\} \)中,\(S_{n}\)是前\(n\)项之和,若\({a}_{1}=1,{a}_{n+1}= \dfrac{1}{3}{S}_{n},n∈{N}_{*} \),则\(a_{n}\) \(=\)___________
\((4)\)若\(AB=2\), \(AC= \sqrt{2} BC\),则\({S}_{∆ABC} \)的最大值 .
\((5)\)等比数列\(\{{a}_{n}\} \)中,\({a}_{1}=2 \),\(a_{8}\) \(=4\),函数\(f(x)=(x-a_{1})(x-a_{2})……(x-a_{8})\),则\(f(0)=\)_____\((\)用数字回答\()\)
\((6)\)设\(a < 0\),若不等式\(-{\cos }^{2}x+(a-1)\cos x+{a}^{2}\geqslant 0 \)对于任意的\(x∈R\)恒成立,则\(a\)的取值范围是__________.