求下列方程的通解:
1.sin(x+40度)sin(x-40度)=3/5
2.sinx+sin2x+sin3x=1+cosx+cos2x
請不要跳步~~!!
最好用中文回答及在算式旁邊寫明用了那一條公式
F.4 a.maths2條(複角)
2007-08-12 1:51 am
回答 (2)
2007-08-12 4:39 am
✔ 最佳答案
如下:圖片參考：http://i204.photobucket.com/albums/bb125/jasonchan424/55267.jpg
可以不理複數~~
2007-08-11 20:48:02 補充：
複數係我無聊計出既,可以唔理~~
參考: wiki+Microsoft Math 3.0+ME
2007-08-12 2:53 am
sin(x+40)sin(x-40)=3/5
-1/2(cos(x+40+x-40)-cos(x+40-x+40)=3/5
cos2x-cos40=-6/5
cos2x=-0.4339999...........
cos2x=cos115.7188529
2x=360n+-115.7188529
x=180n+-57.85942647//
-1/2(cos(x+40+x-40)-cos(x+40-x+40)=3/5
cos2x-cos40=-6/5
cos2x=-0.4339999...........
cos2x=cos115.7188529
2x=360n+-115.7188529
x=180n+-57.85942647//
收錄日期: 2021-04-13 13:58:41
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070811000051KK03924