1 . 证明:
(1)
.
(2)已知
,
,求证:
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1fc2d308d990e5771657c9f56a0936b.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fbdc8633a22f3b9fb3a789d3818657a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45a173784888adf2946382fa093ba53a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/129f958b08c51df454111d41c6db204f.png)
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2 . 已知
的三边
,
,
成等差数列.
(1)求证:
;
(2)若
不是等边三角形,证明其三边
,
,
的倒数不成等差数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65cf6a68b7a0e5458c9c816404f71ff9.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
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3 . (1)请直接运用任意角的三角比定义证明:
;
(2)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75cd397c31481b526bba6136f925b29d.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5417c231457711c7436efc826c66b45a.png)
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4 . 证明锐角三角形中正弦定理成立,即在锐角
中,
所对边为
,求证
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9c1e84aaa7e1b5c1283075b36c72fb5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1501d4035822b34fcc2378f1e316f159.png)
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5 . 已知三角形
中,角A,B,C所对边分别为a,b,c,
.
(1)求证:角B为钝角;
(2)若
,
,求三角形
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b094f28f5591b0932402ab8d0e93a14.png)
(1)求证:角B为钝角;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7806bf3865558f820a9bace47198fc41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49c13034e0263468ba75ad1705cd57b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
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6 . 如图,在
中,
.求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4cb73e9d976cbfe9c590044fa69dd5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf40643d8abe5b3a14c3d31266cb0aeb.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/5/17/e50388aa-7a94-46c0-abf3-d10825b187f7.png?resizew=212)
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2024高一上·全国·专题练习
7 . 求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e386411b83b22c845bdc90e0111d9f26.png)
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8 . 17世纪法国数学家费马在给朋友的一封信中曾提出一个关于三角形的有趣问题:在三角形所在平面内,求一点,使它到三角形每个顶点的距离之和最小.现已证明:在
中,若三个内角均小于120°,则当点
满足
时,点
到
三个顶点的距离之和最小,点
被人们称为费马点.根据以上知识,已知在
中,
,
,
,
为
内一点,则
的最小值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc3229917a0b4d72138d3c05725c1d9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f08273d339dc5ddbb89aa67bb8205e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/263385aa0b73a4429f9b652f7fa6dc5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a45d458ce755deae9c15645993f6db65.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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9 . 化简与证明:
(1)![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13e01d46f19502dcb7293ad7b02757b7.png)
(2)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13e01d46f19502dcb7293ad7b02757b7.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a0658e17f7857d2334934d62687974a.png)
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10 . 数学里有一种证明方法叫做Proofwithoutwords,也被称为无字证明,是指仅用图象而无需文字解释就能不证自明的数学命题,由于这种证明方法的特殊性,无字证明被认为比严格的数学证明更为优雅与有条理.如下图,点
为半圆
上一点,
,垂足为
,记
,则由
可以直接证明的三角函数公式是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55963a9b9b02737110f57a377b41cb4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/813b1b0327154103afd7a728f00cfeda.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd7192893cff0c527c586d7d45f6dccf.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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