如圖,∠ACB=60°,半徑為1cm的⊙O切BC于點(diǎn)C,若將⊙O在CB上向右滾動(dòng),則當(dāng)滾動(dòng)到⊙O與CA也相切時(shí),
![](http://hiphotos.baidu.com/zhidao/pic/item/a686c9177f3e6709e458fd4b38c79f3df8dc552d.jpg)
圓心O移動(dòng)的水平距離是______cm.
![](http://hiphotos.baidu.com/zhidao/pic/item/060828381f30e9242f6f28804f086e061c95f7bc.jpg)
如圖,當(dāng)圓O滾動(dòng)到圓W位置與CA,CB相切,切點(diǎn)分別為E,F(xiàn);
連接WE,WF,CW,OC,OW,則OW=CF,WF=1,∠WCF=
∠ACB=30°,
所以點(diǎn)O移動(dòng)的距離為OW=CF=WF?cot∠WCF=WF?cot30°=
.