1 . 已知:底与腰之比为
的等腰三角形为黄金三角形.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/23/d906e69c-33ad-47c1-87a1-046eb54ce27b.png?resizew=337)
(1)如图1,
即为黄金三角形尺规作图.已知
,求
长为______,
为______.
(2)如图2,即为正五边形尺规作图.求证:五边形
(所作图形)即为正五边形.
(3)请用另一种方法尺规作图作出正五边形.简要叙述作图方法,无需作图.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/029d393bb07b7140905b85f550519de4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/23/d906e69c-33ad-47c1-87a1-046eb54ce27b.png?resizew=337)
(1)如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
(2)如图2,即为正五边形尺规作图.求证:五边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9142a8490de14a87eda628ffa7e28982.png)
(3)请用另一种方法尺规作图作出正五边形.简要叙述作图方法,无需作图.
您最近一年使用:0次
2 . 将1,2,3,4,5,6,7,8,9这9个数随机填入
的方格表中,每个小方格恰填写一个数,且所填数各不相同,则使每行、每列所填数之和都是奇数的概率是________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0e329a94337ada7c88a4fad9b92f0eb.png)
![](https://img.xkw.com/dksih/QBM/2018/12/10/2093628058075136/null/STEM/50ff08a0a99c4080984539a19bc884e3.png?resizew=190)
您最近一年使用:0次