1 . (1)若三角形三内角成等差数列,求证:必有一内角为
.
(2)若三角形三内角成等差数列,而且三边又成等比数列,求证:三角形三内角都是
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
(2)若三角形三内角成等差数列,而且三边又成等比数列,求证:三角形三内角都是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
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真题
2 . 已知
为正整数.
(1)设
,证明:
;
(2)设
,对任意
,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75929e19a42baf63a439894dad69b906.png)
(1)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e1dd675bb62d076f5be59a781197802.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/797e33636f377b31dbb0323577f5639c.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab905ff8e2cf71cfcd68888ffa3f2c0b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01f3b42f09b41461d1c42c654f57fdc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93fe9db2871e6c73dcff65751c21d8a1.png)
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