1 . 如图,圆O是四边形
的外接圆,
是
的直径,
是
的切线,
交
的延长线于点E.
;(用两种方法证明)
(2)若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4611ceb2a28f7a7e4d24266d7f99b22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cac237a6b1ab506b80dc8af809b7a405.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f979d5406af7e951f386dbb55a9617eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff7d2a2da5144f0bf6ce091c56b3d5a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
您最近一年使用:0次
名校
2 . 阅读材料:当一个三角形的两个内角有倍数关系时,此三角形会有一些特殊的性质,如图,
中,
,我们称之为省重三角形,做
,小明发现以下性质并给出如下证明:
在
上取一点E,使
,连接
,
∵
,
,
∴
,
∴
,
∵
,
∴
,
∴
,
∴
,
∴
,即![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b7504023d3887bae858c6a0a8d0d3b7.png)
请直接应用小明发现的规律,完成下列问题:
(1)如图1,已知:在省重
中,
,
,
,则
的面积
________.
(2)如图2,在省重
中,
,F为
中点,求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/becde6c2696e00bb6c8936c6fba10a99.png)
(3)如图3,平行四边形
,对角线交于点O,
,
,
,
,
,求四边形
的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88dc4d22c2c289f6d4494b9c2be84407.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e792b0ef3d542237ed0903194597651.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e792b0ef3d542237ed0903194597651.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48a277db452e76240ec83ec6a2864bdd.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/898611813e24a744cd32df978e1e5c40.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88dc4d22c2c289f6d4494b9c2be84407.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50337fad727f63b856a2cb342cd230c1.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75c5021da4d89ed3ec7f90e7ed802d7f.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49c6a75810f40beeeb4a7de546a94303.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942d4585ad9a70afd4601f1da4527822.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b7504023d3887bae858c6a0a8d0d3b7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/7/f91ea215-d1b0-48ed-89dd-ebf15d8a4cd5.png?resizew=358)
请直接应用小明发现的规律,完成下列问题:
(1)如图1,已知:在省重
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f08273d339dc5ddbb89aa67bb8205e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32f01c4faacedfe56f5127d6c0cc63cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
(2)如图2,在省重
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/becde6c2696e00bb6c8936c6fba10a99.png)
(3)如图3,平行四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d320f180419175d75eebc618cc458b39.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86afd4f2661a9208c4e600e318408777.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1481cad5968b766f7b309541ed1b252.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48813b8fc61cdb0c54fbc6a2e4bbd30b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbc39144b305c67d44410d41053a1d28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
您最近一年使用:0次
3 . 在中点复习课中,刘老师提出了如下问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/29/34f59f50-8471-403e-a5c4-4bc3a8fecaad.png?resizew=359)
如图1,在
中,点D为
的中点,连接
,若
,求
的取值范围.
【初步分析】
小明经过分析,决定延长
到E,使
,连接
,可得到
,进而在
中得到
的取值范围,于是可求得
的取值范围.
(1)请回答:
①如图1,连接
,由已知和作图能得到
的理由是______.
A.
B.
C.
D.![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5eb2decaa6be2df36a5e4b7fabf585d.png)
②求得
的取值范围是______.
A.
B.
C.
D.![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a6731ca8823b4b3d78367a1cb86f52.png)
【感悟探究】
小明经过反思发现,解题时,条件中若出现“中点”“中线”字样,可以考虑延长中线构造全等三角形,把分散的已知条件和所求证的结论集合到同一个三角形中.
于是小明尝试用这种方法证明“中位线定理”
如图2,
分别是
的边
的中点,求证:
,且
.
小明延长
至F,使
,连接
.
(2)请帮助小明完成证明.
【感悟拓展】
小明经过再次反思发现,解题时,条件中若出现多个“中点”字样,还可以考虑用中位线来研究中位线和三角形底边的数量关系和位置关系.请解决以下问题:
(3)如图3,在等边三角形
中,点P为射线
位于点C右侧的一个动点,将线段
绕点P逆时针旋转
得到线段
,点C的对应点为点D,连接
,点Q为
的中点,连接
.若
,当
时,直接写出
的长度.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/29/34f59f50-8471-403e-a5c4-4bc3a8fecaad.png?resizew=359)
如图1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8f83dded14ac36a1b267a52e0e8522d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
【初步分析】
小明经过分析,决定延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df34369163e511f14028168cb0b21186.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af7d19b5c22d55256a532764d4a8a5b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80651f797ab9dccfd7163c605b091ad5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
(1)请回答:
①如图1,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30344bc4e9906892f903e1f0b691c18.png)
A.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6720e36b02193db161c61d4017673760.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5a290f047f50481318d040c604d72f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9beb8b968744573e593ac28451c69729.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5eb2decaa6be2df36a5e4b7fabf585d.png)
②求得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
A.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb89f323547493204e1550f32e94e9e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12b04633aebfef3b31813acf2f221355.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/288d232ff62a35acdf9bf8e706b95aa7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a6731ca8823b4b3d78367a1cb86f52.png)
【感悟探究】
小明经过反思发现,解题时,条件中若出现“中点”“中线”字样,可以考虑延长中线构造全等三角形,把分散的已知条件和所求证的结论集合到同一个三角形中.
于是小明尝试用这种方法证明“中位线定理”
如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91e1e4115d78e625e9e0f47cdade3286.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e675a92cad72c65aa4071b9d9e226090.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/066cd386723885c535ea720f5817847a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0584568387d42bb65fff6fe354f1117a.png)
小明延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e9a9618018d717926540d1452f76e44.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
(2)请帮助小明完成证明.
【感悟拓展】
小明经过再次反思发现,解题时,条件中若出现多个“中点”字样,还可以考虑用中位线来研究中位线和三角形底边的数量关系和位置关系.请解决以下问题:
(3)如图3,在等边三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c0927afc571a7c966c98192040979e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f53330c107f8245290a5a42c3d356acd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/809f2107a6172278be8675645f1c186d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
您最近一年使用:0次
名校
4 . 已知:在
中,
,
,
是
边上的动点,将线段
绕点
顺时针旋转
得到线段
.
在线段
上时,求证:
是
的中点;
(2)如图2,连接
,取线段
的中点
,连接
,直接写出
的大小并证明;
(3)若
是
的中点,
,直接写出
的最小值为______.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fffa3d9c32da53b0ea0c338012ea20c.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/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.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/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
(2)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0023e53eafba27ad50f9a9d3a4207d70.png)
(3)若
![](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/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
您最近一年使用:0次
2024-03-24更新
|
246次组卷
|
3卷引用:北京市十一晋元中学2023-2024学年九年级下学期月考数学试题
北京市十一晋元中学2023-2024学年九年级下学期月考数学试题2024年北京市东直门中学中考零模数学试题(已下线)第六章第03讲 三角形的中位线(5类热点题型讲练)-【帮课堂】2023-2024学年八年级数学下册同步学与练(北师大版)
5 . 已知:如图,在四边形
中,
与
不平行,E,F,G,H分别是
,
,
,
的中点.
(1)求证:四边形
是平行四边形;
(2)当
,四边形
是怎样的四边形?证明你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/8/a52feb1d-bc57-47b8-a7a3-ed371a801ae1.png?resizew=171)
(1)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f100dcfa7803db6eb233e2e7f2dab.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c220eadc312101e2fb89dfe920f7b30d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f100dcfa7803db6eb233e2e7f2dab.png)
您最近一年使用:0次
6 . [背景呈现]
如图1,在四边形
中,
,E、F分别是
的中点,求证:
.在下面的括号内,填上推理的根据.
并延长
交
延长线于点G,
∵
,
∴
(_______________),
又∵点F是
中点,
∴
,
∵
,
∴
(______________),
∴
,
又∵点E是
中点,
∴
(____________________),
因此,结论
成立.
[关联运用]
已知在等腰
和等腰
中,
,点G、 F分别是
的中点,
.
(1)如图2,若点D、E分别在
上,则
的长度是_____
(直接写出结果);
(2)如图3,若点E在
上,点D在
的外部,求
的长.
如图1,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a11029ca6b4b9e7f777af0280cf163c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ba48366317ebea1c9dd5e4e67e03092.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e5a8690d29193d4bd3dcb13ae5fed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a11029ca6b4b9e7f777af0280cf163c.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7415115fba424d8f5dea97690ee78ae.png)
又∵点F是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cf5b86308e9f777a6611503ba8d0e9e.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/010e7ce7cb0cfbcb286d36d3d75148c8.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2aa4e7beedeb92c39e0c3a9801024cf2.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4340ce1070c1188a23196179f8840b38.png)
又∵点E是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32a6dd4344319ea7bf98b5873a422606.png)
因此,结论
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2e5a8690d29193d4bd3dcb13ae5fed4.png)
[关联运用]
已知在等腰
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7d2a15061b3f15f299a1c9c1ba66084.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01ac9b2894db7b1577f94596a52a86a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c4320b5bb88f112357bf2700e1924ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39fffea0a09c9b030e95aeb13c6ab240.png)
(1)如图2,若点D、E分别在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3355e2fa0ac6c675f02ee36c3ced4f2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0e57a13c665af88f326c9890072bf73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
(2)如图3,若点E在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0e57a13c665af88f326c9890072bf73.png)
您最近一年使用:0次
7 . 三角形中位线定理证明:三角形的中位线平行于第三边,并且等于第三边的一半;
已知:如图,D、E分别是
的边
、
中点.
求证:
,
.
下面是某学习小组探究证明思路时发现的三种添加辅助线的方法,请选择其中一种,完成证明.
方法1:延长
至点F,使
,连接
;
方法2:过点C作
交
的延长线于F;
方法3:过E作
交
于F,过A作
交
的延长线于点G.
已知:如图,D、E分别是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c436f108fd4921dae15ecff19270237e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/950e82a0f9712457f2dd9f8a93f8a217.png)
下面是某学习小组探究证明思路时发现的三种添加辅助线的方法,请选择其中一种,完成证明.
方法1:延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea921dc90bddec20f5bcc184b2e83962.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
方法2:过点C作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe9f641563e8533a5bb39188aa7cc182.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
方法3:过E作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c197d8b99f2eb7477947e53461b5d548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e5c72449a461d10ec2bfae6e08b82c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7c57b07f75e97d9f84718bd495ebcf4.png)
您最近一年使用:0次
8 . 中考新考法 阅读理解题阅读下列材料,完成相应任务.
直角三角形斜边上的中线等于斜边的一半如图①,在
中,
,
是斜边
上的中线.求证:
.
分析:要证明
等于
的一半.可以用
倍长法
将
延长一倍,如图②,延长
到点
,使得
.连接
,
.可证四边形
是矩形,由矩形的对角线相等得
,将直角三角形斜边上的中线与斜边的数量关系转化为矩形对角线的数量关系,进而得到
.
(2)上述证明方法中主要体现的数学思想是 ;
A. 转化思想 B. 类比思想 C. 数形结合思想 D. 从一般到特殊思想
(3)如图③,点
是线段
上一点,
,点
是线段
上一点,分别连接
,
,点
,
分别是
和
的中点,连接
.若
,求
的长.
直角三角形斜边上的中线等于斜边的一半如图①,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29c7d01c3618d579121d95d41a63c565.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81aa5816176014df488313a050b8942b.png)
分析:要证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1a9c6a736e6eac98a676fa3232db5a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b442a3e7f84b17be0d7631a7e422ff1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28d5ee30c1e98de68935c5446c727819.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b505f99976276247d709f9529be5064b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9f79d7939c88e9702962e5917cad290.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6b41d4070854edfaa24071137b314cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/164e1cc74e41a2a55d3767c006392bfd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7595bdaea3dfa548c0fcfe3708387476.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81aa5816176014df488313a050b8942b.png)
(2)上述证明方法中主要体现的数学思想是 ;
A. 转化思想 B. 类比思想 C. 数形结合思想 D. 从一般到特殊思想
(3)如图③,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad63ab71efa010821650ffe08bd907f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1ffb98f1e3c1317c0db403d3af04bdc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88929f4ba0851730d5f941d426b87548.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0213c5787a5a6b38d11bceca5567f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d87448e09eaa816e50ae92d111d5ded6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b6bcdfb8d0f14f5e6492169596758fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d87448e09eaa816e50ae92d111d5ded6.png)
您最近一年使用:0次
名校
9 . 如图,在
中,
,
是
的中位线,
是
的中线.求证:
.
(1)请把证法1补充完整;
(2)试用不同的方法证明
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74e46fb91464159b80eab7c28a926b4e.png)
证法1:∵![]() ![]() ∴ ![]() ∵ ![]() ![]() ![]() ∴ ![]() ∴ ![]() |
(1)请把证法1补充完整;
(2)试用不同的方法证明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74e46fb91464159b80eab7c28a926b4e.png)
您最近一年使用:0次
名校
10 . 对“中位线定理”逆向思考,可得命题:在三角形内,经过三角形一边中点,且与另一边平行的线段,是三角形的中位线.这是一个真命题,填空并证明.
如图:已知
是
的中点, ,
求证: .
如图:已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
求证: .
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/21/878c9e64-3ac9-43ab-8c1a-d47a32c86448.png?resizew=150)
您最近一年使用:0次