(sin^2(x) + 2cos(x) - 1) / (sin^2(x) + 3cos(x) - 3) = (cos^2(x) + cos(x) )/(-sin^2(x))
PLEASE! URGENT! TRIG IDENTITIES! AHHH!
Can someone prove this trig identity?
2016-05-13 1:11 pm
回答 (1)
2016-05-13 1:49 pm
✔ 最佳答案
(sin²x + 2cosx - 1) / (sin²x + 3cosx - 3)= (1 - cos²x + 2cosx - 1) / (1 - cos²x + 3cosx - 3)
= (- cos²x + 2cosx) / (- cos²x + 3cosx - 2)
= - cosx (cosx - 2) / - (cosx - 2)(cosx - 1)
= cosx / (cosx - 1)
= cosx(cosx + 1) / ((cosx - 1)(cosx + 1))
= (cos²x + cosx) / (cos²x - 1)
= (cos²x + cosx) / (- sin²x)
收錄日期: 2021-04-30 21:33:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160513051157AAMA6gb