问题提出:射到平面镜上的光线(入射光线)和变向后的光线(反射光线)与平面镜所夹的角相等.如图1,
是平面镜,若入射光线
与水平镜面夹角为
,反射光线
与水平镜面夹角为
,则
.
,则直接写出
的大小.
(2)数学探究:如图2,有两块平面镜
,
,且
,入射光线
经过两次反射,得到反射光线
.
完成如下问题:
①若
,直接写出
的度数.
②求证:
.
拓展运用:有两块平面镜
,
,入射光线
经过两次反射,得到反射光线
,光线
与
相交于点
,如图3,图4.若
,
.直接写出
,
满足的数量关系.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2c3d2cba96f6f03520c0b3f6e4da03e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fdcf6bcc8458140c579219e5dd91efba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
(2)数学探究:如图2,有两块平面镜
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf3369e0ea90e8d5cf4b6b3c45c0fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c0b06dc01c30d13f64be2ac6a1d811e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
完成如下问题:
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f586d178cb0f69dd900967766ba8950a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c4c3c0a34dc21292fa32befd58d8f82.png)
②求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
拓展运用:有两块平面镜
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf3369e0ea90e8d5cf4b6b3c45c0fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.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/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b5632d211b06594939fddc35a28b66e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcf49467debcd06abf3d4d056b5a66d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
更新时间:2024-05-11 22:19:04
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相似题推荐
解答题-问答题
|
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【推荐1】若将一副三角板按如图1所示的方式放置(其中
,
,
),将三角形
固定不动,三角形
绕点
逆时针旋转,旋转角为
.
(1)如图2,若
,则
,
.
(2)如图3,若
于点
,则
与
平行吗?请说明理由.
(3)如图4,若
,则图中有哪两条线平行?请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb747b59d3dabb8de3680d736fa8267.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af5b3967aa677f18e92912d2397f4907.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1e39bfb2f4be18735fc76997a96582.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9a32bd7a1b78b5a0ec562c4025aea8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/2/3c9d9666-4fa5-4b6e-a7b4-3ac9f6523d8f.png?resizew=654)
(1)如图2,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0b65ca62ce90b4879f58884e826c669.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cc310194575262fb45352c2fbc19868.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5324ce5fd43c5b05e8fad764880f7b3.png)
(2)如图3,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68fbbd17c89f03dbb61cd6ffdb9a0344.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
(3)如图4,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
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【推荐2】在物理学中,平面镜反射光线的规律是:射到平面镜上的光线和被反射出的光线与平面镜所夹的锐角相等.
如图
,一束光线
射到平面镜
上,被
反射后的光线为
,则入射光线
、反射光线
与平面镜
所夹的锐角
.
【简单应用】(
)如图
,有一口井,已知入射光线
与水平线
的夹角为
,现放置平面镜
,可使反射光线
正好垂直照射到井底(即射线
),
与水平线的夹角
的度数为______.
【类比拓展】(
)如图
,有两块平面镜
,且
,入射光线
经过两次反射,得到反射光线
.由以上光的反射定律,可知入射角与反射角相等,进而可以推得他们的余角也相等,即:
.在这样的条件下,求证:
.
【尝试探究】(
)两块平面镜
,且
,入射光线
经过两次反射,得到反射光线
.如图
,光线
与
相交于点
,则
的度数是多少?(用含
的式子表示)(三角形内角和
)
如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
【简单应用】(
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d36581140ebac5d28438ea63b1b23b65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74e63f1bc4759d55d1db2f113debcbf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd0dc942dc5a587e3c638df0d42c76b.png)
【类比拓展】(
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d8d57d44169246811fb5ed7e55c6b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c0b06dc01c30d13f64be2ac6a1d811e.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/366662c4db40bdfa03d9c50cf07f2674.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
【尝试探究】(
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d8d57d44169246811fb5ed7e55c6b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a84261efd0ff6fafdc55cd446c1a5f68.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/b8860d9787671b53b1ab68b3d526f5ca.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/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6282292819434a8905a212427613fd85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfe639eab78eafd2d40ea70aa5d3f21d.png)
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解答题-问答题
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解题方法
【推荐1】在
中,
,点
是直线
上一点(不与
、
重合),以
为一边在
的右侧作
,使
,
,连接
.
(1)如图,当点
在线段
上,如果
,则
______度.
![](https://img.xkw.com/dksih/QBM/2021/1/19/2639635893248000/2642196928290816/STEM/3bf3a64e-6428-4013-930e-db4ba0baf2c3.png)
(2)设
,
.
①如图,当点
在线段
上移动时,
、
之间有怎样的数量关系?请直接写出你的结论.
![](https://img.xkw.com/dksih/QBM/2021/1/19/2639635893248000/2642196928290816/STEM/ddec99ba-604b-49a4-959d-449dec259a00.png)
②如图,当点
在线段
的反向延长线上移动时,
、
之间有怎样的数量关系?请说明理由.
![](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/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.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/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2d212c1709b8e72a055cf1b5381ef64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43651721f6c0ea4cf50a33054ecc5d60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
(1)如图,当点
![](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/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b753dbb5a670dd4f5e23bb919e44dda2.png)
![](https://img.xkw.com/dksih/QBM/2021/1/19/2639635893248000/2642196928290816/STEM/3bf3a64e-6428-4013-930e-db4ba0baf2c3.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb2cf0e95fdf1fd8a5b01d3dfd905e08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c49dca0cc635668c549ec80c1d893ed4.png)
①如图,当点
![](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/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://img.xkw.com/dksih/QBM/2021/1/19/2639635893248000/2642196928290816/STEM/ddec99ba-604b-49a4-959d-449dec259a00.png)
②如图,当点
![](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/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://img.xkw.com/dksih/QBM/2021/1/19/2639635893248000/2642196928290816/STEM/61e75e28-cfae-4f91-8d4f-6660a701a57a.png)
您最近一年使用:0次
解答题-证明题
|
适中
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【推荐2】如图,等腰直角
中,
,
,
.点
在
的延长线上,连接
;过点
作
,使
,连接
,
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/b5476de4-cff6-432f-baf3-86efe95874c8.png?resizew=209)
(1)求证:
.
(2)如图,若点
为
的中点,连接
、
;求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d89ba4036a5d18ec4abed44d7fd8e89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38a8ee575ca2160f8c7c8ea9c1156de0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef6d946ec5bc75341f7e5fe400054464.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b1d267eeb09c171c3e847f0597be31c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/b5476de4-cff6-432f-baf3-86efe95874c8.png?resizew=209)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf4dc4d7d30af1cdce660795e0fd7d7c.png)
(2)如图,若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a31df969dd803c2f7eb3d64df2383578.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/540162f8-1016-400a-8d27-6fd3dd5509cb.png?resizew=209)
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【推荐3】认真阅读下面关于三角形内外角平分线的研究片断,完成所提出的问题.
探究1:如图(1)在△ABC中,O是∠ABC与∠ACB的平分线BO和CO的交点,通过分析发现∠BOC=90°+
∠A,理由如下:
∵BO和CO分别是∠ABC和∠ACB的角平分线,∴∠1=
∠ABC,∠2=
∠ACB.
∴∠1+∠2=
(∠ABC+∠ACB)=
(180°-∠A)=90°-
∠A.
∴∠BOC=180°-(∠1+∠2)=180°-(90°-
∠A)=90°+
∠A
探究2:如图(2)中,O是∠ABC与外角∠ACD的平分线BO和CO的交点,试分析∠BOC与∠A有怎样的关系?请说明理由.
探究1:如图(1)在△ABC中,O是∠ABC与∠ACB的平分线BO和CO的交点,通过分析发现∠BOC=90°+
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
∵BO和CO分别是∠ABC和∠ACB的角平分线,∴∠1=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
∴∠1+∠2=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
∴∠BOC=180°-(∠1+∠2)=180°-(90°-
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
探究2:如图(2)中,O是∠ABC与外角∠ACD的平分线BO和CO的交点,试分析∠BOC与∠A有怎样的关系?请说明理由.
![](https://img.xkw.com/dksih/QBM/2018/12/21/2101182881505280/2103847026171904/STEM/ce6fe4d4ab22445dae0acd5d60ae0b90.png?resizew=244)
您最近一年使用:0次
解答题-作图题
|
适中
(0.65)
【推荐1】如图,在
中,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/7/ecd8cd9b-ddae-41c2-85be-315113d425ff.png?resizew=144)
(1)作
的垂直平分线,交
于点
,交
于点
(请用尺规作图,保留作图痕迹,不写作法);
(2)连接
,求
的度数.
![](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/5250d99c74961c4135f1b76c863a4544.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/7/ecd8cd9b-ddae-41c2-85be-315113d425ff.png?resizew=144)
(1)作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.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/2a30f3a8b673cc28bd90c50cf1a35281.png)
(2)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3702b5620dbee356a8e560c78d223ad.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐2】1.一个零件的形状如图所示,按规定∠A应等于120°,∠B、∠D应分别为15°、20°.李叔叔量得∠BCD=145°,就能断定该零件不合格,你能说出其中的道理吗?
![](https://img.xkw.com/dksih/QBM/2013/3/20/1573619895549952/1573619951509504/STEM/01ed9058-7b75-4bc3-88d8-0552774232d9.png?resizew=255)
您最近一年使用:0次