http://i409.photobucket.com/albums/pp172/momoko_deedee/cos.jpg
唔明ar...><
可唔可以explain一下~?
同埋le....乜野係trick function?
trigonometric equation
2009-03-25 1:15 am
回答 (3)
2009-03-25 4:24 am
✔ 最佳答案
trigonometric equation
睇下明唔明~~~~
圖片參考：http://g.imagehost.org/0498/ScreenHunter_01_Mar_24_20_21.gif
2009-03-25 3:49 am
( sqr3 / 2 ) cos x - ( 1 / 2 ) sin x = 1 / 2 --- (*)
As you know, cos ( pi / 6 ) = sqr3 / 2 and sin ( pi / 6 ) = 1 / 2
Therefore (*) can be written as
cos ( pi / 6 ) cos x - sin ( pi / 6 ) sin x = 1 / 2
i.e. cos ( pi/6 + x ) = 1 / 2
As you know, cos ( pi / 6 ) = sqr3 / 2 and sin ( pi / 6 ) = 1 / 2
Therefore (*) can be written as
cos ( pi / 6 ) cos x - sin ( pi / 6 ) sin x = 1 / 2
i.e. cos ( pi/6 + x ) = 1 / 2
2009-03-25 1:46 am
You should know the compound angle formula:
cos(A + B) = cosAcosB - sinAsinB
'trick function' is rare, I have no idea.
cos(A + B) = cosAcosB - sinAsinB
'trick function' is rare, I have no idea.
收錄日期: 2021-04-23 20:42:07
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090324000051KK00959