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1 . 三角比内容丰富,公式很多.若仔细观察,大胆猜想,科学求证,你能发现其中的一些奥秘.请你完成以下问题:
(1)计算:
及
;
(2)根据(1)的计算结果,请你猜想出一个一般性结论,并证明你的结论.
(1)计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9b07d5408015922c0077f1e1374b583.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85b0afde62c59484aac3274e7f1fcc8f.png)
(2)根据(1)的计算结果,请你猜想出一个一般性结论,并证明你的结论.
您最近一年使用:0次
2020-01-23更新
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268次组卷
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2卷引用:上海市青浦高级中学2016-2017学年高一下学期3月质量检测数学试题
2 . 利用公式
,证明:
(1)
;
(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbb006ea697b63a914eb487073f0abe1.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95d314e91c622febc8861ea32dd71fab.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/857ad304c9845431a3c734f41fc198d0.png)
您最近一年使用:0次
2023-12-20更新
|
170次组卷
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6卷引用:人教B版(2019) 必修第三册 逆袭之路 第八章 8.2 三角恒等变换 8.2.1 两角和与差的余弦
人教B版(2019) 必修第三册 逆袭之路 第八章 8.2 三角恒等变换 8.2.1 两角和与差的余弦(已下线)8.2.1两角和与差的余弦导学案(1)广东省珠海市北京师范大学珠海分校附属外国语学校2023-2024学年高一下学期3月月考数学试卷人教B版(2019)必修第三册课本例题8.2.1 两角和与差的余弦人教A版(2019)必修第一册课本例题5.5 三角恒等变换(已下线)5.5.1两角差的余弦公式(第1课时)(导学案)-【上好课】
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解题方法
3 . 如图,已知
的内角
、
、
的对边分别为
、
、
,其中
,且
,延长线段
到点
,使得
,
.
![](https://img.xkw.com/dksih/QBM/2021/4/16/2701270347735040/2703352175058944/STEM/0c6da528-603b-4404-a66d-1e9884d172ba.png?resizew=284)
(1)求证:
是直角;
(2)求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.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)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad5e009486af263893ca8290be72f258.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e762fe2dd40d314915682433b2af063.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/201af318aa0d3167fafa09106e98dd9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d65639672f444b3d4dc6fc4f357ddbd5.png)
![](https://img.xkw.com/dksih/QBM/2021/4/16/2701270347735040/2703352175058944/STEM/0c6da528-603b-4404-a66d-1e9884d172ba.png?resizew=284)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0636e0c3ae734c1ac05ef4d53b1f2a92.png)
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4 . 已知
中,三内角
、
、
的度数成等差数列,边
、
、
依次成等比数列.求证:
是等边三角形.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.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)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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解题方法
5 . 在
中,角
,
,
所对的边分别为
,
,
,且
.
(1)求证:
;
(2)若
,且
的面积为2,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.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)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b74f6929393d07a9399ae179479bf71.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b05d3b8f5c9df891ef6fbcaf12f43207.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b86d43790babcdbbdc03493ee70928.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
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解题方法
6 . 在
中,内角
所对的边分别是
,已知
.
(1)求证:
为等腰三角形;
(2)若
是钝角三角形,且面积为
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df6f452f9c9ac2741f29e0ec66e65cde.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67336ccd79b321083fa8821e524c7467.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c49386fb1d7557c1dc9956a4495e2ca9.png)
您最近一年使用:0次
2020-09-11更新
|
564次组卷
|
5卷引用:江西省宜春市奉新县第一中学2019-2020学年高三上学期第四次月考数学(文)试题
江西省宜春市奉新县第一中学2019-2020学年高三上学期第四次月考数学(文)试题【全国百强校】江西省南昌市江西师范大学附属中学2019届高三三模数学(文)试题云南省昭通市实验中学2018-2019学年高二下学期期末数学试题(已下线)考点17 正、余弦定理及解三角形-备战2021年高考数学(理)一轮复习考点一遍过海南省临高县2023届高三模拟考试数学试题
解题方法
7 . 我国著名数学家华罗庚于
世纪七十年代倡导的“
优选法”,在生产和科学实践中得到了非常广泛的应用,
是黄金分割比的近似值.把一条线段分割为长度为
与
的两部分,使得一部分长与全长之比恰好等于另一部分长与这部分长之比,即
,这个比值叫做黄金分割比,已经证明,以满足黄金分割比的
为腰,
为底边的等腰三角形的底角为
,据此可以计算出该等腰三角形的顶角余弦值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b7f27ebcef70a3ebbbe8d2e53ea0896.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8664a837eed36c57a7af7ce08bf47a4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8664a837eed36c57a7af7ce08bf47a4f.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/c85f9e1e853d25bc69dbca82531ccc8a.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/86d5cc8d752461b4b8ebe89ee91c0ce8.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
8 . 在
中,角
所对的边分别为
.已知
.
(1)证明:
;
(2)若
,
,求
的周长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fe67d2a995a809fb9084ab41ee43200.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9cb21ae875f36d52d0b6f82b0201d0e.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30ebb2603c1da90c22e0abdd5131b0be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/534f33cc16d82470cbff68beffead264.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
您最近一年使用:0次
2020-05-09更新
|
413次组卷
|
2卷引用:河南创新发展联盟2019-2020年度高二下学期第二次联考文科数学试题
9 . 已知
中,内角
、
、
的对边为
、
、
,
三角形
外接圆的半径,证明:
(1)
;
(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.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)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34369422d71dd95c61cdd1b8245d7b6c.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c30b12f8bf54428846cf378ffd5a23b7.png)
您最近一年使用:0次
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解题方法
10 . 已知
,
,
.
(Ⅰ)求证:向量
与
垂直;
(Ⅱ)若
与
的模相等,求
的值(其中
为非零实数).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/afb2a6ac6bb1cb11445577dd97e0fa30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5109992a5bf54faa23355741beb74959.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfa948cb66784cd5839721537ae85542.png)
(Ⅰ)求证:向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73b91254db5ff748150f449c5cdd256c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f1c1dd6b13d92f2cc2eef097e14c07c.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41960bbc66bdc3b28be0138f83f9de5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cfb755a80aa6c04d60627a54115d123.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/628560d39eeb0339fa00c9c15ab2c095.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
您最近一年使用:0次
2020-03-16更新
|
1071次组卷
|
3卷引用:山东省济南外国语学校2019-2020学年高一3月月考数学试题