a-maths!!!!!!
回答 (1)
2008-04-08 1:50 am
✔ 最佳答案
Delta = 0 for (2 sinφ)x2 - 2x - cosφ = 0 has equal roots, i.e.22 - 4 ( 2 sinφ)( - cosφ) = 0
1 + 2 sinφcosφ= 0
sin 2φ= -1
2φ= 3π/ 2
φ= 3π/ 4
參考: My Maths Knowledge
收錄日期: 2021-04-23 20:36:29
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080407000051KK01561