請解X的值,請盡力幫忙 唔該
圖在下
http://h.imagehost.org/view/0002/20100612132
急! 數學解圖
2010-06-12 6:28 pm
回答 (1)
2010-06-12 6:48 pm
✔ 最佳答案
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cosㄥACB = (BC^2 + AC^2 - AB^2) / (2 BC AC)
cosㄥACB = (7^2 + 6^2 - 8^2) / (2*7*6) = 1/4
;
cosㄥACD = cos(180° - ㄥACB) = - cosㄥACB = - 1/4
(AC^2 + DC^2 - AD^2) / (2 AC DC) = -1/4
(6^2 + 5^2 - x^2) / (2*6*5) = -1/4
(61 - x^2) / 60 = -1/4
61 - x^2 = - 15
x^2 = 76
x = 2√19
收錄日期: 2021-04-21 22:13:16
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100612000051KK00377