數學問題,關於5角形
2010-09-21 5:13 am
圖片參考：http://imgcld.yimg.com/8/n/HA00543461/o/701009200145213873372470.jpg
In the figure ,ABCDE is a regular pentagon and ABCF is a parallelogram,
Find ㄥCFD,Is AFD a straight line?
回答 (1)
2010-09-21 5:28 am
✔ 最佳答案
AB = FC ( parallelogram . opp. sides)AB = CD (regular pentagon sides)SoCF = CD ,and ㄥDCF = ㄥDCB - ㄥFCB = 108 - (180 - 108) = 36°So ㄥCFD = (180 - 36)/2 = 72°ㄥAFC + ㄥCFD = 108 + 72 = 180° ,So AFD is a straight line.
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100920000051KK01452