tag:blogger.com,1999:blog-3550204829234352390.post1281712684313718629..comments2024-03-27T09:13:48.546+08:00Comments on 研發養成所 ( Bridan's Blog - 4rdp, For R&D Person ): 訓練數學感 156 ─ 圓錐體的最短距離Bridanhttp://www.blogger.com/profile/17055047757114667099noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-3550204829234352390.post-71392786525251447812021-05-28T17:22:49.576+08:002021-05-28T17:22:49.576+08:00謝謝你的提醒,確實這是一個先上升再下降的線,它是示意圖,我就先暫時不改圖。謝謝你的提醒,確實這是一個先上升再下降的線,它是示意圖,我就先暫時不改圖。Bridanhttps://www.blogger.com/profile/17055047757114667099noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-63164573143900028982021-05-27T22:28:03.320+08:002021-05-27T22:28:03.320+08:00你的最短路徑畫錯了 應該是一個先上升後下降的線你的最短路徑畫錯了 應該是一個先上升後下降的線234https://www.blogger.com/profile/15870984967562282677noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-49900794951708911282017-12-18T15:15:28.694+08:002017-12-18T15:15:28.694+08:00正解,不過我用畢氏定理求解。輔助線過A點垂直OB正解,不過我用畢氏定理求解。輔助線過A點垂直OBBridanhttps://www.blogger.com/profile/17055047757114667099noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-53786788202094722312017-12-16T09:41:32.836+08:002017-12-16T09:41:32.836+08:00在展開圖中,OB射線其實就是角平分線。
使用內分比,得AB=27√7/2 ‧(27/27+13.5)...在展開圖中,OB射線其實就是角平分線。<br />使用內分比,得AB=27√7/2 ‧(27/27+13.5)=(27√7/2)(2/3)=9√7.https://www.blogger.com/profile/16677804023065232981noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-50553288290390586632017-12-11T20:10:01.381+08:002017-12-11T20:10:01.381+08:00加分題,線段 AB 長度多少?
從原題數值看到根號,可以預期這是一條直線不是曲線。加分題,線段 AB 長度多少? <br />從原題數值看到根號,可以預期這是一條直線不是曲線。Bridanhttps://www.blogger.com/profile/17055047757114667099noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-40810567361824996922017-12-10T10:47:45.050+08:002017-12-10T10:47:45.050+08:00正解,這題很像 http://4rdp.blogspot.tw/2010/01/blog-post....正解,這題很像 http://4rdp.blogspot.tw/2010/01/blog-post.htmlBridanhttps://www.blogger.com/profile/17055047757114667099noreply@blogger.comtag:blogger.com,1999:blog-3550204829234352390.post-41823231089610989192017-12-10T10:33:01.467+08:002017-12-10T10:33:01.467+08:00此題的步驟如下:
1.劃出錐體展開圖
2.計算圓心角,小圓周長/2‧錐體斜邊‧π
3.找出C點的對應...此題的步驟如下:<br />1.劃出錐體展開圖<br />2.計算圓心角,小圓周長/2‧錐體斜邊‧π<br />3.找出C點的對應位置,畫出直線距離,會發現所求是一個以13.5cm 27cm為兩邊,120度為夾角的對邊。<br />4.畫高,利用特殊角可以求出<br />13.5√7,即27√7/2.https://www.blogger.com/profile/16677804023065232981noreply@blogger.com