5.
\((1)\)等差数列\(\left\{ {{a}_{n}} \right\}\)中,\({{a}_{2}}=9,{{a}_{5}}=33,\)则\(\left\{ {{a}_{n}} \right\}\)的公差为________
\((2)\)在\(\triangle ABC\)中,若\(a=3\),\(b= \sqrt{3}\),\(∠A= \dfrac{π}{3}\),则\(∠C\)的大小为_______
\((3)\)已知数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和\({{S}_{n}}={{n}^{2}}+2n-1\),则通项\({{a}_{n}}=\)______
\((4)\)已知数列\(\{{{a}_{n}}\}(n\in {{N}^{*}})\),其前\(n\)项和为\({{S}_{n}}\),给出下列四个命题:
\(①\)若\(\{{{a}_{n}}\}\)是等差数列,则三点\((10,\dfrac{{{S}_{10}}}{10})\)、\((100,\dfrac{{{S}_{100}}}{100})\)、\((110,\dfrac{{{S}_{110}}}{110})\)共线;
\(②\)若\(\{{{a}_{n}}\}\)是等差数列,且\({{a}_{1}}=-11\),\({{a}_{3}}+{{a}_{7}}=-6\),则\({{S}_{1}}\)、\({{S}_{2}}\)、\(…\)、\({{S}_{n}}\)这\(n\)个数中必然
存在一个最大者;
\(③\)若\(\{{{a}_{n}}\}\)是等比数列,则\({{S}_{m}}\)、\({{S}_{2m}}-{{S}_{m}}\)、\({{S}_{3m}}-{{S}_{2m}}(m\in {{N}^{*}})\)也是等比数列;
\(④\)若\({{S}_{n+1}}={{a}_{1}}+q{{S}_{n}}(\)其中常数\({{a}_{1}}q\ne 0)\),则\(\{{{a}_{n}}\}\)是等比数列.
其中正确命题的序号是_________ \(.(\)将你认为的正确命题的序号都填上\()\)