用首尾相连的四条线段连接九个点:
1、要求
这四条直线必须一笔完成。
2、分析题义
要求关键点:四条直线,一笔完成,穿过9点
结果:四条直线(线段)
3、试验作图
无非就是三种线段横线、竖线、斜线,如图所示
4、分析问题
发现其实三条横线和竖线都可以将九个点串完,但是无法一笔画完,即便再加上一条斜线,此方案不行。反复演示,会发现一横一竖两条斜线,既能一笔画完,又能串比较多的点,但依然有两点串不到,如图所示。
5、发散思维
将所圈直线平行按箭头方向往外拉,拉到那没有线的两个点上。
6、得出答案
拉过之后,发现有点别扭,但是点都过线了,而且现也没增加,还是四条直线,唯一变得就是直线的交点不在黄点上了。
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