本區搜索:
Yahoo!字典

# [M2] Trigonometry (1)

## Trigonometry (1)

TOP

 風之男 學院師父 發短消息 加為好友 當前離線 2# 大 中 小 發表於 2021-1-7 05:10 PM (第 202 天) 只看該作者 [顯示] [隱藏] Well... what have you attempted so far? At least in my opinion, this is not a "do your homework for you" forum, so please show some of your work or thought process, be it correct or not. Anyhow, here are some hints: (a) If you get stuck at proving identities, you can always try to prove "LHS-RHS=0" instead. In the solution below, the method of completing square is used, but we're adding/subtracting the middle term instead of the usual last term. If you've tried the "LHS-RHS=0" approach, you might get an idea why I chose to complete square (or I've been factoring x^4+y^4 way too many times lately). (b) Just repeated usage of sinx=cos(pi/2-x). FULL SOLUTION, STRONGLY ADVICE YOU ATTEMPT THE PROBLEM BEFORE VIEWING https://www.docdroid.net/4nzV7H4/document-pdf [ 本帖最後由 風之男 於 2021-1-7 06:12 PM 編輯 ] UID216418 帖子933 精華0 積分115 閱讀權限40 在線時間1569 小時 註冊時間2011-5-4 最後登錄2021-7-28  查看詳細資料 TOP

## 回覆 2# 風之男 的帖子

Thank you very much for your hints.

Honestly, I and my classmates have tried several times before we decided to post on the forum for help,
we can promise you that we have tried our very best before seeking for help.

TOP

##### 引用:

Thank you very much for your hints.

Honestly, I and my classmates have tried several times before we decided to post on the forum for help,
we can promise you that we have tried our very best befo ...
No worries. Just know that learning math is about getting stuck most of the time.
I want to know where you get stuck on so I could give an appropriate response.

Good luck and have fun with math!

TOP

 takwing1 學院師兄 發短消息 加為好友 當前離線 5# 大 中 小 發表於 2021-1-11 01:54 AM (第 198 天) 只看該作者 a) LHS = (cos^2 theta + sin^2 theta)^2 - 2sin^2theta cos^2theta = 1 - (1/2) (2sin theta cos theta)^2 = 1- (1/2) sin^2 2theta 齊齊溫 DSE資源網: https://www.study-together.com 個人: http://www.takwing.idv.hk UID72887 帖子501 精華0 積分58 閱讀權限30 在線時間134 小時 註冊時間2008-5-23 最後登錄2021-5-9  查看詳細資料 TOP
 重要聲明:小卒資訊論壇 是一個公開的學術交流及分享平台。 論壇內所有檔案及內容 都只可作學術交流之用，絕不能用商業用途。 所有會員均須對自己所發表的言論而引起的法律責任負責(包括上傳檔案或連結)， 本壇並不擔保該等資料之準確性及可靠性，且概不會就因有關資料之任何不確或遺漏而引致之任何損失或 損害承擔任何責任(不論是否與侵權行為、訂立契約或其他方面有關 ) 。