prove:
2sinx + sin2x = (2sin^3x)/(1-cosx)
a.maths
2007-02-20 7:09 pm
回答 (1)
2007-02-20 7:23 pm
✔ 最佳答案
2sinx + sin2x= 2sinx + 2sinxcosx
= 2sinx(1 + cosx)
= 2sinx(1 + cosx)(1 - cosx) / (1 - cosx)
= 2sinx[1 - (cosx)^2] / (1 - cosx)
= 2sinx(sinx)^2 / (1 - cosx)
= 2(sinx)^3 / (1 - cosx)
收錄日期: 2021-04-12 18:01:08
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070220000051KK00904