1 . 如图,
的内心为
,
、
、
分别是边
、
、
的中点,证明:直线
平分
的周长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e105760638b22b26ff8bec4354255e4c.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/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9abaeba15f3abdd877bc701af52c5cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/445d7497f41656d5d3115dafef213972.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72cb97395ebc5ee1b212afb7a97b985c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/892447cf-89df-42b6-a265-f87e3795ba71.png?resizew=182)
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2 . (1)已知P是矩形ABCD所在平面上的一点,则有
.试证明该命题.
(2)将上述命题推广到P为空间上任一点的情形,写出这个推广后的命题并加以证明.
(3)将矩形ABCD进一步推广到长方体
,并利用(2)得到的命题建立并证明一个新命题.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a4444709816cede0c3a735af9f2ec90.png)
(2)将上述命题推广到P为空间上任一点的情形,写出这个推广后的命题并加以证明.
(3)将矩形ABCD进一步推广到长方体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd694ad3a4733c7c84aaa7946aeea4de.png)
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2019-01-28更新
|
312次组卷
|
3卷引用:2018年全国高中数学联赛湖南省预赛B卷
3 . 如图,在凸四边形ABCD中,M为边AB的中点,且MC=MD.分别过点C、D作边BC、AD的垂线,设两条垂线的交点为P.过点P作
与Q.求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d84733f9dc908ceb11459cc2aed580ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c613757b80a67dfad94b6e8c9c140f.png)
![](https://img.xkw.com/dksih/QBM/2019/1/28/2128338057494528/2128624691085312/STEM/282f71a0c8c042468d120a46f02d1fa1.png?resizew=162)
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4 . 已知点P、Q在△ABC内,且
,则
等于.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942639bea5d7bcd343a078af0d5e44f8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edb24d40a0166c737af1ba7381315970.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2018高三·黑龙江·竞赛
5 . 如图,在
中,
,
的平分线AC于点E,过点E作BE的垂线交AB于点F,
是
的外接圆且
交BC于点D.
![](https://img.xkw.com/dksih/QBM/2019/1/28/2128337543864320/2128607650504704/STEM/715461d9-fdbd-403c-9526-0947d2dcc9c7.png)
(1)求证:AC是
的切线;
(2)过点E作
,垂足为H,求证:CD=HF;
(3)在(2)的条件下,若CD=1,EH=3,求BF及AF的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a69550d878381f6e8fb436e88638f070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f2ea13010e2399194be2a681310543e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://img.xkw.com/dksih/QBM/2019/1/28/2128337543864320/2128607650504704/STEM/715461d9-fdbd-403c-9526-0947d2dcc9c7.png)
(1)求证:AC是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
(2)过点E作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3bb34308698b377df58ef5441aeec76.png)
(3)在(2)的条件下,若CD=1,EH=3,求BF及AF的长.
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2018高三·黑龙江·竞赛
名校
6 .
中,
,C所对的边分别为
,
.
(1)求
;
(2)若
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c0ae8e92dd3119d41f2c830ea526516.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ace74bfb716753490ebe0e740ff5baa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a2060b4b87b84ef46a38566d7954596.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29c0a6efe18abe173b91498ff750cd62.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9dd8dc7ac339df242fa74391768120ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/377d8f968709442464168c01380441e8.png)
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2019-01-28更新
|
320次组卷
|
4卷引用:2018年全国高中数学联赛黑龙江省预赛
7 . 设点O为三角形ABC内一点,且满足关系式
,则 ![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d1c51b50b63eb06307d899b04bb630.png)
_____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/673b8bc2cf72812f05a45b04c23492fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d1c51b50b63eb06307d899b04bb630.png)
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8 . 如图,设
的外接圆为
,
的角平分线与BC交于点D,M为BC的中点.若
的外接圆
分别与AB、AC交于P、Q、N为PQ的中点.证明:(1)BP=CQ;(2)
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9ccea461315a9d05aa0193b937d4bfe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/146a63bac5ecd239f2696801e8eaa0b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e2bd387ad688461e522af5acf2108d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cfd30442c116ab096d645838774a41b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce649bd23a80acdad4f743f8a14a748e.png)
![](https://img.xkw.com/dksih/QBM/2019/1/28/2128336789356544/2128582196051968/STEM/6959239e-704b-4735-a6ac-c887065b0581.png)
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9 . 在△ABC中,
,
,则△ABC的面积最大值为_____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d70dc2c20619a4fc12a0cfda59af5b69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adabea3b2fca1d80f014260fd63b61b5.png)
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2019-01-28更新
|
569次组卷
|
2卷引用:2018年全国高中数学联赛河北省预赛 高二试题
10 . 在矩形ABCD中,已知AB=3,BC=1,动点P在边CD上.设
,
,则
的最大值为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/482002db587fa5dcc33454ebe5ace500.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec3fcca37520855783dc1295b16f40b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c314634cd48deaaf425f88fa5177864.png)
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