prove the following trigonometric identities:
tan^2(90-x)-cos^2x=tan^2(90-x)cos^2x
trigonometric identities
2011-03-28 9:45 pm
回答 (1)
2011-03-28 10:13 pm
✔ 最佳答案
LHS = tan^2(90-x) - cos^2x
= 1/(tan^2x) - cos^2x * sin^2x / sin^2x
= cos^2x / sin^2x - cos^2x / sin^2x * sin^2x
= cos^2x / sin^2x * ( 1 - sin^2x )
= 1/(tan^2x) * cos^2x
= tan^2(90-x)cos^2x
= RHS
參考: ME
收錄日期: 2021-04-15 17:29:03
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110328000051KK00436