题目
题型:不详难度:来源:
⑴计算:
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101929-35482.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101929-36933.gif)
⑵如图所示,△ABC中,∠C=90°,∠B=30°,AD是△ABC的角平分线,若AC=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101929-92243.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101929-56479.gif)
求线段AD的长.
答案
(1)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101930-12171.gif)
(2)2
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101930-37537.gif)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101930-26237.gif)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101930-12171.gif)
(2)解:∵△ABC中,∠C=90º,∠B=30º,
∴∠BAC=60º,
∵AD是△ABC的角平分线,
∴∠CAD=30º, 1分
∴在Rt△ADC中,
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101930-15356.gif)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101929-92243.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101931-31259.gif)
="2" . 4分
核心考点
举一反三
已知:△ABC是任意三角形.
⑴如图1所示,点M、P、N分别是边AB、BC、CA的中点.求证:∠MPN=∠A.
⑵如图2所示,点M、N分别在边AB、AC上,且
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101922-10705.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101922-41457.gif)
⑶如图3所示,点M、N分别在边AB、AC上,且
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101922-71072.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101922-55402.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101923-52463.gif)
(请直接将该小问的答案写在横线上.)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101917-22576.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101918-13930.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101918-25801.png)
交于H点。若ÐABC=ÐEFC=70°,ÐACB=60°,ÐDGB=40°,则下列哪 一组三角形相似?
A.△BDG,△CEF | B.△ABC,△CEF ( | C.△ABC,△BDG | D.△FGH,△ABC |
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101911-18473.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101911-93083.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101911-18473.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101912-45903.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101912-96162.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101912-71271.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101912-71212.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101913-19160.png)
A.8 | B.8.8 | C.9.8 | D.10 |
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-41199.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-41199.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-28766.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-14816.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-41199.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-58030.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-98898.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-44942.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-88718.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-13167.png)
(甲) 作ÐACP、ÐBCP之角平分线,分别交
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-41199.png)
(乙) 作
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101906-84278.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101907-85329.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101905-41199.png)
A.两人都正确 | B.两人都错误 | C.甲正确,乙错误 | D.甲错误,乙正确 |
![](http://img.shitiku.com.cn/uploads/allimg/20191103/20191103101901-18709.png)
A.60 | B.61.8 | C.67.2 | D.69 |
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