题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075836-24546.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075836-31631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075837-56183.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075837-37219.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075837-36078.png)
(1)求S关于x的函数关系式及该函数的定义域;
(2)当x取何值时,液晶广告屏幕MNEF的面积S最小?
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075837-83996.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-32392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-72075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-72646.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-89859.png)
解析
试题分析:解:(1)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-46452.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075839-33246.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075839-46843.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075837-37219.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075839-96569.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075839-82337.png)
定义域为
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-32392.png)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075840-65857.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075840-73567.png)
令
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075840-37128.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075840-99950.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075840-49833.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075841-82844.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075841-21144.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-89859.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075841-92979.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075842-30945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075842-69624.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-89859.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075841-92979.png)
∴当
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075842-34523.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-89859.png)
答:当AN长为
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-72075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-72646.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075838-89859.png)
点评:研究数学模型,建立数学模型,进而借鉴数学模型,对提高解决实际问题的能力,以及提高数学素养都是十分重要的.建立模型的步骤可分为: (1) 分析问题中哪些是变量,哪些是常量,分别用字母表示; (2) 根据所给条件,运用数学知识,确定等量关系; (3) 写出
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075842-24300.png)
核心考点
试题【(14分)如图,ABCD是正方形空地,边长为30m,电源在点P处,点P到边AD,AB距离分别为m,m.某广告公司计划在此空地上竖一块长方形液晶广告屏幕,.线段M】;主要考察你对空间几何体的视图与直观图等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075831-63981.jpg)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075824-32256.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075824-64090.png)
A.144 | B.![]() | C.![]() | D.64 |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075816-69523.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075816-13205.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075755-43384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075755-98825.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-93413.png)
(Ⅰ)证明:平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-95264.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-16591.png)
(Ⅱ)设
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-32792.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075755-43384.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075755-98825.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-17695.png)
(ⅰ)当点C在圆周上运动时,求
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-17695.png)
(ii)记平面
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075757-14975.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075757-58654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075757-23716.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075756-17695.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075757-96154.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075751-91747.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075751-73771.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021075751-81363.jpg)
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