名校
解题方法
1 . 在
中,角
所对的边分别为
,
(1)若
,用
表示
;
(2)已知
分别为
的中点,若
,求证:
.
![](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)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2f2498c7b9d8dd5650c0324f6a8f807.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a670e260518d5224e588db3e293e868.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db46b8b8e0cb1d567637646a343ee973.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1308feea4b34a358cd93dc9c53664a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8beaa11e068d72ee0f8579901f9c639c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a6e2948f17dc94a1af0648c14d01809.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c897a54f2e36bc4b52fba74b41c89d2d.png)
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名校
2 . 向量是数学中一个很神奇的存在,它将“数”和“形”完美地融合在一起,在三角形中就有很多与向量有关的结论.
例如,在△ABC中,若O为△ABC的外心,则
,
证明如下:取AB中点E,连接OE,可知OE⊥AB,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea6802ef27003ef7cd848fef0c1a49d4.png)
.
利用上述材料中的结论与方法解决下面的问题:
在△ABC中,a,b,c分别内角A,B,C的对边,满足a>c且2bcos A=3c,
,设O为△ABC的外心,
若
,则x-2y=________ .
例如,在△ABC中,若O为△ABC的外心,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/407606be418586f81c469557c6af677d.png)
证明如下:取AB中点E,连接OE,可知OE⊥AB,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea6802ef27003ef7cd848fef0c1a49d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ddc61d9ebf445ae1b9cf8f5c3ac9c34.png)
利用上述材料中的结论与方法解决下面的问题:
在△ABC中,a,b,c分别内角A,B,C的对边,满足a>c且2bcos A=3c,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e3053b7064d4e38994f321586183b7b.png)
若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea68288b67c5264c6a6b1aaad0ca9ca5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/84b44bc5-e4f0-4312-9167-3df68d452102.png?resizew=158)
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名校
3 . 古希腊数学家普洛克拉斯曾说:“哪里有数学,哪里就有美,哪里就有发现……”,对称美是数学美的一个重要组成部分,比如圆,正多边形……,请解决以下问题:
![](https://img.xkw.com/dksih/QBM/2021/4/28/2709589299273728/2759660379553792/STEM/1eef0c92360245aa8e4c2533a2eebb6e.png?resizew=191)
(1)魏晋时期,我国古代数学家刘徽在《九章算术注》中提出了割圆术:“割之弥细,所失弥少,割之又割,以至于不可割,则与圆合体,而无所失矣”,割圆术可以视为将一个圆内接正n边形等分成n个等腰三角形(如图所示),当n变得很大时,等腰三角形的面积之和近似等于圆的面积,运用割圆术的思想,求
的近似值(结果保留
).
(2)正n边形的边长为a,内切圆的半径为r,外接圆的半径为R,求证:
.
![](https://img.xkw.com/dksih/QBM/2021/4/28/2709589299273728/2759660379553792/STEM/1eef0c92360245aa8e4c2533a2eebb6e.png?resizew=191)
(1)魏晋时期,我国古代数学家刘徽在《九章算术注》中提出了割圆术:“割之弥细,所失弥少,割之又割,以至于不可割,则与圆合体,而无所失矣”,割圆术可以视为将一个圆内接正n边形等分成n个等腰三角形(如图所示),当n变得很大时,等腰三角形的面积之和近似等于圆的面积,运用割圆术的思想,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/440ce692fa6eef853b95f4c9ddba9294.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86ebba6ed1add0fe647c0226614b9290.png)
(2)正n边形的边长为a,内切圆的半径为r,外接圆的半径为R,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d41b98a3d788ea1255c209653fb728d3.png)
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2021-07-08更新
|
560次组卷
|
4卷引用:江苏省镇江中学2020-2021学年高一下学期期中数学试题
江苏省镇江中学2020-2021学年高一下学期期中数学试题(已下线)数学与文学贵州省黔西南州金成实验学校2021-2022学年高一下学期4月质量监测数学试题(已下线)压轴题三角函数新定义题(九省联考第19题模式)练
4 . 如图,在三棱柱
中,侧棱
底面
,
,
为
的中点,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/15/fdf623af-6192-4a27-87b9-ba0ef6747590.png?resizew=152)
(1)求证:
平面
;
(2)求
与
所成角的余弦值;
(3)求三棱柱
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4339a40ae9d1947ec3a4b3e2fa3a16cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f8eeeea1c9652cacce976f8129cf520.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/15/fdf623af-6192-4a27-87b9-ba0ef6747590.png?resizew=152)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1c920d02068d0e63ffdab70786c526d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a935b7d21a103a264b6e96ecf82dbe4a.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
(3)求三棱柱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
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5 . 已知等边三角形
分别是边
上的三等分点,且
(如图甲),将
沿
折起到
的位置(如图乙),
是
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/18/fee79488-59ec-4eb1-9cf0-973366d5735d.png?resizew=399)
(1)求证:
平面
;
(2)若二面角
的大小为
,求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42ab05980824d7403b26cc3d3aa5436f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dec2ca6438c82b43f746057d8129885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d42218a68301d770accaaefb96b19f8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3aa2a83fed9bf4cb09d84a980452e346.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10d8eb4a9f462ca0c1d49c3fe91e720d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/18/fee79488-59ec-4eb1-9cf0-973366d5735d.png?resizew=399)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd0285afe567ca0b32f0ccafc30167cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9afac7c616bbb14e1ed428a3c507c7dc.png)
(2)若二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/628d6fc46c651e0c783b81a123a7b229.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f785147690f83dcee0a0bc6c327e75a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a98287a302228ece1fa53c5c66c590f.png)
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6 . 关于公式sin(α+β)=sinαcosβ+cosαsinβ的证明,前人做过许多探索.对于α,β均为锐角的情形,推导该公式常可以通过构造图形来完成.
(1)填空,完成推导过程(约定:只考虑α,β,α+β均为锐角的情形)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/74832972-d57f-4c50-a998-af69ed5c4481.png?resizew=196)
证明:构造一个矩形如图形1,在这个矩形GHMN中,点P在边MN上,点Q在边GN上,QT⊥HM,垂足为T,∠HPQ=90°,设HQ=1,∠QHP=α,∠PHM=β.
在直角三角形QHP中,QP=sinα,PH=cosα,
在直角三角形PHM中,PM=___________,
在直角三角形QPN中,∠QPN=β,PN=sinαcosβ,
在直角三角形HQT中,QT=___________,
因为QT=PM+PN,所以sin(α+β)=sinαcosβ+cosαsinβ.
(2)请你运用提供的图形和信息(见图形2)完成公式(约定:只考虑α,β均为锐角的情形)的推导.
(1)填空,完成推导过程(约定:只考虑α,β,α+β均为锐角的情形)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/74832972-d57f-4c50-a998-af69ed5c4481.png?resizew=196)
证明:构造一个矩形如图形1,在这个矩形GHMN中,点P在边MN上,点Q在边GN上,QT⊥HM,垂足为T,∠HPQ=90°,设HQ=1,∠QHP=α,∠PHM=β.
在直角三角形QHP中,QP=sinα,PH=cosα,
在直角三角形PHM中,PM=___________,
在直角三角形QPN中,∠QPN=β,PN=sinαcosβ,
在直角三角形HQT中,QT=___________,
因为QT=PM+PN,所以sin(α+β)=sinαcosβ+cosαsinβ.
(2)请你运用提供的图形和信息(见图形2)完成公式(约定:只考虑α,β均为锐角的情形)的推导.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/45cdfb0b-d14f-4cfc-9bf5-fdd541880c43.png?resizew=155)
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解题方法
7 . 如图,四边形
中,已知对角线
,且满足
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/12/d33946a3-23d7-4bc0-8ff3-30bca62729c4.png?resizew=146)
(1)求证:
;
(2)若△
为锐角三角形,设四边形
面积为
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bb5b12692517a39c320f99a479eb055.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d4d00b86b2f067b902baf6e52f0faab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7355730155322ae2a9a0e397774b830a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/12/d33946a3-23d7-4bc0-8ff3-30bca62729c4.png?resizew=146)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90f7efe2f99f5cb6801841171feab6b.png)
(2)若△
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83ea27b72194b40ad10fb5f7e312099d.png)
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名校
解题方法
8 . 在
中,内角
,
,
的对边分别是
,
,
,若
,
.
(1)求角
;
(2)若
为
的角平分线,证明:
.
![](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/e65397f11ea8af736f38debadf420c4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faaeeac3ad7c1946c4ebfb17a49e2e31.png)
(1)求角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b6e1e4294a8d83e0119ac5e91af71d4.png)
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名校
解题方法
9 . 在
中,内角
,
,
的对边分别为
,
,
,的面积为
,若
.
(1)求
;
(2)若
,求证:
是直角三角形;
(3)若
为锐角三角形,
为
边上的一点,若
为
的角平分线,求
的取值范围.
![](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/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6413910e82e2556dbbeeda01ade6073e.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f77b0d66a686e44a201f4699b162dcd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2605b6816431ab1ef826e8b161c5a914.png)
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10 . 在
中,角A,B,C的对边分别为a,b,c,
,角B的平分线交AC于点D,
.
(1)求角B的大小;
(2)证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da48400bdf008b043796cf3a550fcd67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/714cc3707bba3bfdb56e251999be8592.png)
(1)求角B的大小;
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f27695066fdfd0357bdb22469c4a67c5.png)
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