已知数列|an|是首相a1=4.公比q不等于1的等比数列,Sn是其前n项和,且 4a1,a6,-2a3成等差数列(1)求公比q的值(2)求Tn=a2+a4+a6+.+a2n的值3.△ABC的三个内角为A,B,C.当A为? 时,cosA+2cos(B+C)/2取得最大值,且这
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![已知数列|an|是首相a1=4.公比q不等于1的等比数列,Sn是其前n项和,且 4a1,a6,-2a3成等差数列(1)求公比q的值(2)求Tn=a2+a4+a6+.+a2n的值3.△ABC的三个内角为A,B,C.当A为? 时,cosA+2cos(B+C)/2取得最大值,且这](/uploads/image/z/2434862-38-2.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B0%E5%88%97%7Can%7C%E6%98%AF%E9%A6%96%E7%9B%B8a1%3D4.%E5%85%AC%E6%AF%94q%E4%B8%8D%E7%AD%89%E4%BA%8E1%E7%9A%84%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%2CSn%E6%98%AF%E5%85%B6%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E4%B8%94+++4a1%2Ca6%2C-2a3%E6%88%90%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%281%29%E6%B1%82%E5%85%AC%E6%AF%94q%E7%9A%84%E5%80%BC%282%29%E6%B1%82Tn%3Da2%2Ba4%2Ba6%2B.%2Ba2n%E7%9A%84%E5%80%BC3.%E2%96%B3ABC%E7%9A%84%E4%B8%89%E4%B8%AA%E5%86%85%E8%A7%92%E4%B8%BAA%2CB%2CC.%E5%BD%93A%E4%B8%BA%3F++++%E6%97%B6%2CcosA%2B2cos%28B%2BC%29%2F2%E5%8F%96%E5%BE%97%E6%9C%80%E5%A4%A7%E5%80%BC%2C%E4%B8%94%E8%BF%99)
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