(a) 試把 √3 cos x + sin x 化成 r sin(x + α)的形式 , 其中 r > 0 且
0°≦α≦360°。
(b) 求 √3 cos x + sin x = 0 的通解。
A . Maths
2008-07-06 4:17 am
回答 (2)
2008-07-06 9:15 am
✔ 最佳答案
The answers are as follows:圖片參考：http://i320.photobucket.com/albums/nn347/old-master/080705_M1a.jpg?t=1215277849
圖片參考：http://i320.photobucket.com/albums/nn347/old-master/080705_M1b.jpg?t=1215278012
2008-07-06 01:16:02 補充：
「通式」應為「通解」。
2008-07-06 4:32 am
(a)
√3cosx+sinx
=sinx+√3cosx
=2[sinx(1/2)+cosx(√3/2)]
=2sin(x+30)
(b)
√3cosx+sinx=0
2sin(x+30)=0
sin(x+30)=0
x+30=180,360,390
x=150,330,360
2008-07-05 20:34:50 補充：
(a)
√3cosx+sinx
=sinx+√3cosx
=2[sinx(1/2)+cosx(√3/2)]
=2sin(x+60)
(b)
√3cosx+sinx=0
2sin(x+60)=0
sin(x+60)=0
x+60=180,360,390
x=120.300,330
2008-07-05 20:35:52 補充：
x=120°,300°,330 °
√3cosx+sinx
=sinx+√3cosx
=2[sinx(1/2)+cosx(√3/2)]
=2sin(x+30)
(b)
√3cosx+sinx=0
2sin(x+30)=0
sin(x+30)=0
x+30=180,360,390
x=150,330,360
2008-07-05 20:34:50 補充：
(a)
√3cosx+sinx
=sinx+√3cosx
=2[sinx(1/2)+cosx(√3/2)]
=2sin(x+60)
(b)
√3cosx+sinx=0
2sin(x+60)=0
sin(x+60)=0
x+60=180,360,390
x=120.300,330
2008-07-05 20:35:52 補充：
x=120°,300°,330 °
收錄日期: 2021-04-23 20:33:33
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https://hk.answers.yahoo.com/question/index?qid=20080705000051KK02328