题目
题型:不详难度:来源:
(1)若花园的面积为192m2, 求x的值;
(2)若在P处有一棵树与墙CD,AD的距离分别是15m和6m,要将这棵树围在花园内(含边界,不考虑树的粗细),求花园面积S的最大值.
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-24026.jpg)
答案
解析
试题分析:(1)方程的应用解题关键是找出等量关系,列出方程求解. 本题等量关系为:矩形的面积为192.
(2)由在P处有一棵树与墙CD,AD的距离分别是15m和6m,求出x的取值范围,根据二次的性质求解即可.
试题解析:(1)∵AB=xm,∴BC=
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-31631.png)
根据题意,得
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-98663.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-13879.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-36909.png)
∴x的值为12m或16m.
(2)∵根据题意,得
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024245-83042.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024246-24020.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024246-46764.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024246-96219.png)
∴当
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024246-48920.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024246-66657.png)
核心考点
试题【在美化校园的活动中,某兴趣小组想借助如图所示的直角墙角(两边足够长),用28m长的篱笆围成一个矩形花园ABCD(篱笆只围AB,BC两边),设AB=xm.(1)若】;主要考察你对二次函数定义等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024204-66201.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024205-83254.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024205-79494.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024205-32349.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024205-85963.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024206-21653.png)
(1)若点D的横坐标为-5,求抛物线的函数表达式;
(2)若在第一象限的抛物线上有点P,使得以A,B,P为顶点的三角形与△ABC相似,求
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024205-83254.png)
(3)在(1)的条件下,设F为线段BD上一点(不含端点),连接AF,一动点M从点A出发,沿线段AF以每秒1个单位的速度运动到F,再沿线段FD以每秒2个单位的速度运动到D后停止. 当点F的坐标是多少时,点M在整个运动过程中用时最少?
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024206-97888.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024157-44324.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024158-15838.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024158-22335.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024158-50062.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024158-45642.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024159-27224.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024159-58670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024159-31460.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024159-68048.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024159-12102.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024200-45039.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024200-68424.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024200-32463.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191019/20191019024200-14048.png)