kk5032019 2021-4-16 09:59
證明 cos(45+A) - sin(45-A) = 0 ?
[[i] 本帖最後由 kk5032019 於 2021-4-16 09:09 PM 編輯 [/i]]
top11 2021-4-17 18:40
[quote]原帖由 [i]kk5032019[/i] 於 2021-4-16 09:59 AM 發表 [url=https://www.discuss.com.hk/redirect.php?goto=findpost&pid=534198189&ptid=29829724][img]https://www.discuss.com.hk/images/common/back.gif[/img][/url]
證明 cos(45+A) - sin(45-A) = 0 ? [/quote]
LHS
= cos(45° + A) - sin(45° - A)
= sin[90° - (45° + A)] - sin(45° - A) 因為 cos x = sin(90° - x)
= sin(45° - A) - sin(45° - A)
= 0
= RHS