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解题方法
1 . 秦九韶是我国南宋时期的著名数学家,他在著作《数书九章》中提出,已知三角形三边长计算三角形面积的一种方法“三斜求积术”,即在
中,
,b,c分别为内角A,B,C所对应的边,
.若在
中有
,则利用“三斜求积术”求
的面积为__________ .
![](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/fcbd1d383e2504d147db03bbb1f503b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12b210ea541e00e985d0c4f0c5ffdfe4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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2 . 解放碑是重庆的标志建筑物之一,因其特存的历义内涵,仍牵动着人们敬仰的目光,在海内外具有非凡的影响.我校数学兴趣小组为了测量其高度
,在地面上共线的三点C,D,E处分别测得顶点
的仰角为
,且
,则解放碑的高
约为( )(参考数据:
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b362d799bcb77946ba460344d24df71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec3cd04250b6433c113451da0c0325f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dad09268b7cb8bfcbea010cb6d2a29e.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
3 . 在
中,角
所对的边分别是
,若
是
边上的一点,且
.
(1)若
时,求
面积的最大值;
(2)若![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d319424e5bd9c657b252d5edde7a9b79.png)
①求角
的大小;
②当
取得最大值时,求
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce7af7c5df749c6fa9bbe87faa72c66d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88f2599ca8b6b683e57a82699c8b1ebb.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/c13377d1b9792367317b4cd0a8242eec.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0c42206023d239aa78646e76fa7cb8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d319424e5bd9c657b252d5edde7a9b79.png)
①求角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d4231aebdebd43211cdeb5cf0db6f4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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解题方法
4 . 在△ABC中,内角A,B,C的对边分别为a,b,c,
.若
,
,则△ABC的面积为_____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bddbb0fe305bf2b041f076f46c885e47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03837b3769eda7f0d3804cc5ad4a6d60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60b97bb18e5ca34d22b5e827316a122a.png)
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5 . 如图,在
中,
为钝角,
,
,
.过点
作
的垂线,交
于点
,
为
延长线上一点,连接
,若
.
的长;
(2)证明:
;
(3)设
,
,是否存在实数
,使得
恒成立?若存在,求出
的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080ca48cd27d4bf9d9ef084b558fc17a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4feca46892420550b89640eeb6efa4bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef5f3e6682ff3bbb22f5f837468c5e74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3719cea07e8f138a4d7818536712282.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b61054f941aa4f57e9f92bd510d2bdd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55dddd64d22de704d8cdefccc521ecd7.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0b34e72825d8122b50e52c3a08f35a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c58d500e2ec5ae5f62c3b5f28348c62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/200fc2c6a285ba2b4322ace4ed0a9758.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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6 . 定义在封闭的平面区域D内任意两点的距离的最大值称为平面区域D的“直径”.如图,已知锐角三角形的三个顶点A,B,C在半径为1的圆上,角的对边分别为a,b,c,若
.
(2)分别以
各边为直径向外作三个半圆,这三个半圆和
构成平面区域D,求平面区域D的“直径”的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c334d38c555a600eac96e974a61471d.png)
(2)分别以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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7 . 如图1所示,在
中,点
在线段
上,满足
,
是线段
上的点,且满足
,线段
与线段
交于点
.
,求实数
的值;
(2)若
,求实数
的值;
(3)如图2,过点
的直线与边
分别交于点
,设
,
;
(ⅰ)求
的最大值;
(ⅱ)设
的面积为
,四边形
的面积为
,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0296bb542907b81fc0c0d96f916d3c2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ffe1c7041b1b338246d456672db377b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/abf80148409afb32ced0b4f59f1ba709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0627c5fbc080e858cea342516ec0f0df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b0fffbec1fe851795dfdd448bf0d165.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40afbc01f47b02602acee4b39c1fbc91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
(3)如图2,过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dec2ca6438c82b43f746057d8129885.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61cb96903ddcfe069075ef87760ff6a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5cd10329cdcf48bf8cc331e79790a35.png)
(ⅰ)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1adebff9fb726cd58eda1ef994890901.png)
(ⅱ)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c105d6ba18fbb0581fb982175e2eac9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6480f384476190883f06c0289c7519.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ad5a9147b25285124851a61c7d1a24a.png)
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8 . 已知在
中,内角
所对的边分别为
,分别以
为直角边的等腰直角三角形的面积依次是
,且
.
(1)求
;
(2)若
,求
的面积.
![](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/76f0649064a085fb74c997fb507a9b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcf4e20ea341827ce5f9552daee39462.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04b6969c6e977b06cccb68c899ba5329.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c716fed2744c50ea25cce1b87c42903a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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解题方法
9 . 在△ABC中,a,b,c分别是角A,B,C的对边,其外接圆半径为R,内切圆半径为
,满足
,△ABC的面积
,则( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7551011cfb75b26f35b07d6617c6a18b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fadd09b5fc6588f126014bfd5931847.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d6bce7218a37c07febb9965806c0e32.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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