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见内!

Posted by davydc at 2006-02-17 21:09:19 on Problem 2242
In Reply To:abc/4s利用什么原理？ Posted by:hdm2968 at 2006-02-17 19:57:22

设任意一个三角形的三边为a, b, c, 边a所对的角为A. 所求外接圆半径为R

根据任意三角形面积公式, 得到        bcsinA/2 = S

再根据正弦定理, 得到            2RsinA = a

两式一除, 得到          (bc/2) / (2R) = S/a

整理, 就得到            R = abc/(4S)

Followed by:

Re:见内! (42) v123 2006-04-22 20:46:43
- Re:见内! (8) acm_test 2006-04-23 18:46:44
- 前面那个是对的，你这个是内接圆 (0) waterine 2006-11-11 10:18:52
  - Re:前面那个是对的，你这个是内接圆 (13) dosxp 2008-07-09 20:38:41

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