如图,
,D是
的中点,
平分
.
(1)试说明:
;
(2)若
,试判断
的形状,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ab41054fa9ce51b68e78d9c0cf398d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764509115979e9958101808383672ec0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77fb91bbadadc0dfd49182f7b836d129.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/22/5048d4aa-635c-4e0d-bdd6-b5a6ea10541a.png?resizew=175)
(1)试说明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75a91778530fee017af63165397d36b4.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cccde778c619848076ea8c11b0b13a12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
更新时间:2024-01-22 11:03:34
|
相似题推荐
解答题-证明题
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【推荐1】如图所示,
是
的角平分线,
,垂足为E,
交
的延长线于点F,若
恰好平分
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/e3c64624-0c9b-49ff-b8cc-d059caff1b67.png?resizew=143)
(1)求证:
;
(2)若
,求
的面积.
![](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/68fbbd17c89f03dbb61cd6ffdb9a0344.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f572de8798c6eb993ede7606cf7402e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d786ee723231d4ca87eb9d011a378b5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/1/e3c64624-0c9b-49ff-b8cc-d059caff1b67.png?resizew=143)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2efe9c84b49a5bb9d08e97f5fc7a0362.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/172143efb1e6a114d8b538a5b7acba08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab2a2834d80ff574e79eae8ca8d4e94f.png)
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名校
【推荐2】如图,在
中,E是
的中点,连接
并延长交
的延长线于点F.
;
(2)若
,
.求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d5d886a2c8138bdacfcf980e6999351.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09c57d4c6ddf04ef6eaa2987378b434b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60b8651eaec2fa0303aadf2eae67f75c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/060705794ef87cc71dac40c57f27b1d2.png)
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解答题-问答题
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【推荐1】综合与实践∶
【问题背景】鲜艳的中华人民共和国国旗始终是当代中华儿女永不褪色的信仰,国旗上的每颗星都是标准五角星,为了增强学生的国家荣誉感、民族自豪感等,数学老师组织学生对五角星进行了较深入的研究,其中智慧数学小组发现国旗上五角星的五个角都是顶角为
的等腰三角形,对此三角形产生了极大的兴趣并展开探究.
【探究发现】如图 1,在
中, ![](https://staticzujuan.xkw.com/quesimg/Upload/formula/093c6b5aeaa7e581ad4345e137c24c92.png)
(1)操作发现:将
折叠,使边
落在边
上,点C的对应点是点E,折痕交
于点 D,连接
,则
°,设
, 那么
(用含x的式子表示);
(2)进一步探究发现:顶角为
的等腰三角形的底与腰的比值为
这个比值被称为黄金比.请在 (1)的条件下证明:
.
【拓展应用】当等腰三角形的底与腰的比等于黄金比时,这个三角形叫做黄金三角形.例如,图 1 中的
是黄金三角形.
(3)如图2, 在菱形
中,
.求这个菱形较长对角线的长.
【问题背景】鲜艳的中华人民共和国国旗始终是当代中华儿女永不褪色的信仰,国旗上的每颗星都是标准五角星,为了增强学生的国家荣誉感、民族自豪感等,数学老师组织学生对五角星进行了较深入的研究,其中智慧数学小组发现国旗上五角星的五个角都是顶角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7b398c95494eddc79939f16e66cf4da.png)
【探究发现】如图 1,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/093c6b5aeaa7e581ad4345e137c24c92.png)
(1)操作发现:将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1b48221615e7f6d622b32fac9b069c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86bcfb91bf2911f80be6a2dcf42ae3aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/502a7344464cfa21689eec94792fe51a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d57b4243fa7f6f9c73d11f3123c42ddb.png)
(2)进一步探究发现:顶角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a7b398c95494eddc79939f16e66cf4da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c942a6ae83c85989833ca0ec3cb779ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5156adc8c4bbbebb15d992a26a529484.png)
【拓展应用】当等腰三角形的底与腰的比等于黄金比时,这个三角形叫做黄金三角形.例如,图 1 中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(3)如图2, 在菱形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/168a096c7d47ed44bb5c2688d209c6fc.png)
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解答题-作图题
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【推荐2】如图,点O为平面直角坐标系的原点,点A在x轴上,
是斜边长为2的等腰直角三角形.
(1)以点O为旋转中心,将
按顺时针方向旋转
,得到
.请画出
,并写出点
,
的坐标;
(2)点B和点
可以看做是关于y轴上某个点中心对称吗?如果可以,请直接写出对称中心的坐标;如果不可以,请简要说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2b83beedb3438153e6f728545fe3e03.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/2/841d9f7a-c714-4111-b509-3bb1ad24305a.png?resizew=380)
(1)以点O为旋转中心,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2b83beedb3438153e6f728545fe3e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c02b54dc6b3e1bb6544f47d4c8743fcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91c77b5c57dc6fc40a5ffd77daacc8ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91c77b5c57dc6fc40a5ffd77daacc8ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
(2)点B和点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
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【推荐1】阅读材料:要将多项式
分解因式,可以先把它的前两项分成一组,再把它的后两项分成一组,从而得到:
,这时
中又有公因式
,于是可以提出
,从而很到
,因此有![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66cef7ce25dd7b9bd9df7829e81d5276.png)
,这种方法称为分组法,请回答下列问题:
(1)尝试填空:
________;
(2)拓展应用:已知三角形的三边长分别是
,
,
,且满足
,试判断这个三角形的形状,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66cef7ce25dd7b9bd9df7829e81d5276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd087006962c2183817ca9ee64b12137.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37d5e1f8e23a448c5ad0383acb2a4f7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a024ba7034bd9d8ea94c5f1b7e5b7ea3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a024ba7034bd9d8ea94c5f1b7e5b7ea3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/864dca858f8d7e594f8db9745e25220e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66cef7ce25dd7b9bd9df7829e81d5276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b74d6707823c6fbfd69d7b544ec43f86.png)
(1)尝试填空:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4054e834997e5c85a2d167c983a8bb78.png)
(2)拓展应用:已知三角形的三边长分别是
![](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/1dac9a2f7206d5d1448c260878cd1b57.png)
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【推荐2】如图,△ABC中,∠ACB=90°,点D是边BC上一点,DE⊥AB于点E,点F是线段AD的中点,连接EF,CF.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/22/e3967f05-ba13-4e00-96b6-ac5f5ad9f63c.png?resizew=140)
(1)求证:EF=CF;
(2)若∠BAC=30°,连接EC,试判断△EFC 的形状,并说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/22/e3967f05-ba13-4e00-96b6-ac5f5ad9f63c.png?resizew=140)
(1)求证:EF=CF;
(2)若∠BAC=30°,连接EC,试判断△EFC 的形状,并说明理由.
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