1 . 对于三次函数
(
),给出定义:设
是
的导数,
是
的导数,若方程
有实数解
,则称点
为函数
的“拐点”.某同学经过探究发现:任何一个三次函数都有“拐点”;任何一个三次函数都有对称中心,且“拐点”就是对称中心.设函数
,请你根据这一发现,计算
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4a7a7b93fb8d0714e7d213144d58095.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/de648cd39338d48f2d22eb82a77b4839.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9747a6549da84473cae74bae57ec7d54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8b6894e8c345a035e89ec672503a01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cb9225b977dab891881fd3705a0586b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9747a6549da84473cae74bae57ec7d54.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a805fbd7e09e6702da4e8821022798e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79b752f0f189e5d8666daea73e145dff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea9470db56f4397747215dcb7a48bd6f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09b29a7faa14a6e09d0db2d04f4ced03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75f6f98dd1a623c14d7548da2fb5c60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cabde9778552f95b9a3d8ad63958117d.png)
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解题方法
2 . 《九章算术·商功》:“斜解立方,得两堑堵.斜解堑堵,其一为阳马,一为鳖臑.阳马居二,鳖臑居一,不易之率也.合两鳖臑三而一,验之以棊,其形露矣.”刘徽注:“此术臑者,背节也,或曰半阳马,其形有似鳖肘,故以名云.中破阳马,得两鳖臑,鳖臑之起数,数同而实据半,故云六而一即得.”
如图,在鳖臑ABCD中,侧棱AB⊥底面BCD;
(1)若
,
,
,试求异面直线AC与BD所成角的余弦值.
(2)若
,
,点P在棱AC上运动.试求
面积的最小值.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/22/84152742-e106-43ca-a408-c3b4449bce08.png?resizew=416)
如图,在鳖臑ABCD中,侧棱AB⊥底面BCD;
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/22/6476cb57-a508-4f63-868c-6a74790b42f7.png?resizew=301)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0402dd5ae3db10281f9f1e11738bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/037b342a682cbd4241855a243da3c016.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff9c7cbcc38b28d45c8539710e5b260a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2e1ab67f8e48ad3340cf9d165cd75f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acee03d4bb4667b6c345221b6c9b0fa4.png)
您最近一年使用:0次