解题方法
1 . 已知正项数列
,满足
(其中
).
(1)若
,且
,证明:数列
和
均为等比数列;
(2)若
,以
为三角形三边长构造序列
(其中
),记
外接圆的面积为
,证明:
;
(3)在(2)的条件下证明:数列
是递减数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62e567d7e9761951a266953c8d5042ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5111d17779f9cda4a54c61cfefc2f166.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cec12441802f71e803efaf2c62ee588.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55057cbf3fe8a213b1fa07a6d815a7dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00f098a8e28129cc098a094af19b4224.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ec12a9a60f82467bf7bf834a9a9b1f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/602470bce6410555c9696c5a9e5ab7f8.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/077b55d1a38aed465eeb76f208425cee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b54256d8902384e68221e9a95cde739c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54c3e9493b3005f0e995e9b5c323433d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36f8e6f90b4a8eb54ffe62bf8c7cd618.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54c3e9493b3005f0e995e9b5c323433d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/838582d690e0d124d0355782b094ebbb.png)
(3)在(2)的条件下证明:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/846fa57d92d6ad44d6a0cafad1e71ed4.png)
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