①以一適合長(zhǎng)度為半徑,以A為圓心作圓交L于點(diǎn)M,N
![](http://e.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=e9fb91af902397ddd62c900269b29e8f/562c11dfa9ec8a13efe4ffa8f603918fa1ecc0f8.jpg)
②分別以M,N為圓心,作圓弧,兩圓弧分別交于P,Q兩點(diǎn)
![](http://h.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=43ff9d435ab5c9ea62a60be5e5099a38/8601a18b87d6277fe94b997029381f30e924fc19.jpg)
③連接PQ,就是所求垂直線(xiàn)啦
![](http://g.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=44c3a5ffe850352ab1342d0e6373d7ca/e824b899a9014c08103682ed0b7b02087bf4f46d.jpg)
二,
過(guò)直線(xiàn)外的A點(diǎn)作已知直線(xiàn)L的平行線(xiàn)
①在上面基礎(chǔ)上做好一條垂直線(xiàn)
![](http://h.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=dce133d72fdda3cc0bb1b02631d91539/3c6d55fbb2fb4316faf5d03221a4462308f7d394.jpg)
②延長(zhǎng)垂線(xiàn),用圓規(guī)截取,使得AB=AC
![](http://a.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=0cc5f17e1c950a7b756046c23ae14ee1/d1160924ab18972b94caaa82e7cd7b899f510a81.jpg)
③再以B,C為圓心,適合長(zhǎng)度為半徑做圓弧,相交于G,H
![](http://f.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=a4b68147b90e7bec238f0be71f1e9500/472309f790529822efb9ac8bd6ca7bcb0b46d4f4.jpg)
④連接GH就是那條平行線(xiàn)了
![](http://g.hiphotos.baidu.com/zhidao/wh%3D600%2C800/sign=7c8776f0d53f8794d3aa4028e22b22cc/a6efce1b9d16fdfa419353a6b58f8c5495ee7bff.jpg)
那就用我們兩把直尺吧