cos^2θ - tan^2θsin^2θ=???
回答 (2)
2011-07-25 11:33 am
✔ 最佳答案
cos²θ - tan²θsin²θ= cos²θ - (sin²θ/cos²θ)sin²θ
= cos²θ - (sin⁴θ/cos²θ)
= (cos⁴θ - sin⁴θ)/cos²θ
= (cos²θ + sin²θ)(cos²θ - sin²θ)/cos²θ
= (cos²θ- sin²θ)/cos²θ
= 1 - tan²θ
參考: micatkie
2011-07-25 9:36 pm
cos^2θ - tan^2θsin^2θ
cos^2θ-(sin^2θ/cos^2θ)(sin^2θ)
cos^2θ-(sin^4θ/cos^2θ)
(cos^4θ-sin^4θ)/cos^2θ
(cos^2θ-sin^2θ)/cos^2θ(It can be answer)
1-tan^2θ(It is better)
cos^2θ-(sin^2θ/cos^2θ)(sin^2θ)
cos^2θ-(sin^4θ/cos^2θ)
(cos^4θ-sin^4θ)/cos^2θ
(cos^2θ-sin^2θ)/cos^2θ(It can be answer)
1-tan^2θ(It is better)
收錄日期: 2021-04-13 18:07:41
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https://hk.answers.yahoo.com/question/index?qid=20110725000051KK00133