题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235106-78871.png)
答案
解析
分析:由DE为三角形ABC的中位线,根据三角形中位线定理得到DE平行于BC,且DE等于BC的一半,再由两直线平行得到两对同位角相等,根据两对对应角相等的两三角形相似,可得出三角形ADE与三角形ABC相似,且相似比为1:2,根据相似三角形的面积之比等于相似比的平方,得到三角形ADE与三角形ABC面积之比,由三角形ADE的面积即可求出三角形ABC的面积.
解:∵DE是△ABC的中位线,
∴DE∥BC,DE=
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235106-42990.png)
∴∠ADE=∠B,∠AED=∠C,
∴△ADE∽△ABC,且相似比为1:2,
∴S△ADE:S△ABC=1:4,又S△ADE=4,
则S△ABC=4S△ADE=16.
故答案为:16
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235055-42594.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235055-61479.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235056-58882.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235056-73422.png)
(1)求的
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235056-50133.png)
(2)在矩形OACB中,点P是线段BC上的一动点,直线PD⊥AB于点D,与
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235055-61479.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235057-27879.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235057-57458.png)
①求
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235057-57458.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235057-27879.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235057-27879.png)
②⊙Q是△OAB的内切圆,求当PE与⊙Q相交的弦长为2.4时点P的坐标。
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235052-42346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235053-14648.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235052-42346.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235053-14648.png)
A.4 | B.6 | C.8 | D.32 |
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235046-47314.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235040-41064.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235040-16114.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235041-23273.png)
求AB的长.
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235041-87031.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-14245.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-20758.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-18618.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-98883.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-67192.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-53502.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235020-43177.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235020-52457.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235020-78104.png)
(1)在
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235020-93393.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235020-38668.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-89894.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-20758.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-74085.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-64918.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-85642.png)
(2)如图二,若
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-74171.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-77871.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-80923.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235019-18618.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-74171.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-64918.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-54283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-52028.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-77871.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-13051.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-89894.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-67267.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-67267.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-74171.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-50707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-62630.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-95741.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-41113.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-54283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-54283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-41113.png)
(3)在(2)的条件下,当
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235021-54283.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235023-25849.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191102/20191102235022-67267.png)
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