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1 . 在给出的下列命题中,正确的是( )
A.已知![]() ![]() ![]() ![]() |
B.![]() ![]() ![]() ![]() ![]() |
C.![]() ![]() ![]() ![]() ![]() |
D.![]() ![]() ![]() ![]() |
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2021-08-14更新
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4卷引用:湖北省荆、荆、襄、宜四地七校考试联盟2020-2021学年高一下学期期中联考数学试题
湖北省荆、荆、襄、宜四地七校考试联盟2020-2021学年高一下学期期中联考数学试题湖北省襄阳市第五中学2021-2022学年高一下学期期中数学试题浙江省温州市乐清中学2021-2022学年高一(15-18班)上学期12月月考数学试题(已下线)专题07 奔驰定理与四心的相关运算及构造圆解决向量问题-【重难点突破】2021-2022学年高一数学常考题专练(人教A版2019必修第二册)
2 . 我们知道,对一个量用两种方法分别计算一次,由结果相同则可以构造等式解决问题,这种思维方法称为“算两次”原理,又称“富比尼原理”,是一种重要的数学思想.例如:如图甲,在
中,D为
的中点,则
,两式相加得
,因为D为
的中点,所以
,于是
.请用“算两次”的方法解决下列问题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/0d7c5ade-cae3-4880-8831-e03654f37740.png?resizew=457)
(1)如图乙,在四边形
中,E,F分别为
的中点,证明:
.
(2)如图丙,在四边形
中,E,F分别在边
上,且
,
,
,
,
与
的夹角为
,求
.
![](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/1993fedca8d75454f2c45dd7572319a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15275320d949dd581ec1d51d30443bf8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08907cc87d17cbe3dfa70f32e91381b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34d5ef082556fc084f5f2384b1758683.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/0d7c5ade-cae3-4880-8831-e03654f37740.png?resizew=457)
(1)如图乙,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/213d19f241bd032b79ef71acce794748.png)
(2)如图丙,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d93949d8a15aca4e79cedb978590571.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/940099db7ffe6b3f7e70afcfba66750a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/558098da135bc12e7fdca05d14c3848e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efc6e4b936d7a800e839a30c3839574d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16ed75e65e7374c38ffb1f75259a8beb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9795e7f5cb9b366776c41d8f3f43942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fdc83becc28e0f43d71427d9e8775d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5bca00fa20e6e80480b9d06d2e52ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c89f40b723898ad6c0238faf87d56621.png)
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