1 . 在直径为5的圆内放入10个点,证明其中必有两点的距离小于2.
您最近一年使用:0次
2021九年级·全国·竞赛
2 . 如图,
分别是
的三边
上任意一点,证明:
中至少有一个三角形的面积不大于
的面积的四分之一.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c5b88ec996d2d117987e7303cefe4ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b372e638a9dbed3bbf92454d816d212.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0066a64af88ca17687b58a5b135ea3f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/10/627731cb-39db-4403-847b-c5ed0f1947f4.png?resizew=148)
您最近一年使用:0次
名校
3 . 如图,在△ABD中,AB
AD,以AB为直径的圆交AD于点M,交BD于点O,延长AO至点C,使OC
AO,连结CD,BC.
(1)求证:四边形ABCD是菱形;
(2)若AM
3,BO![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
,求cos∠DAB.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
(1)求证:四边形ABCD是菱形;
(2)若AM
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2967337e3fcb228dded64ab0c41a17e0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/26/dbc20483-39b3-439f-85f5-089a90187d1a.png?resizew=207)
您最近一年使用:0次