呢條題,求步驟,最好有答案
更新1:
我想問,如果有答案就最好貼埋出黎吧
更新2:
唔記得左,我想求x係乜= =
更新3:
sor,我個fd岩岩先同我講答案一定要x要大過或等於0 細過或等於360
數學,急!!超急.......呢條數一定要超快計
回答 (4)
2008-03-12 7:56 pm
✔ 最佳答案
2sin x + 4cos x = sin x + 3cos x, where 0<= x <=3602sin x - sin x = 3cos x - 4cos x
sin x = - cos x
sin x / cos x = - 1
tan x = - 1
x = - 45
so,
x = 135 or x = 225
you can check it by using your calculator =]
2008-03-12 11:59:01 補充：
第一行where.....
亂左碼
意思即係x大過或等於0 細過或等於360
參考: My maths knowledge
2008-03-12 3:36 am
2sin x 4cos x = sin x 3cos x
2sin x - sin x = 3cos x - 4cos x
sin x = -cos x
sin x + cos x = 0
(sin x + cos x)^2 = 0
(sin x)^2 + 2sin x cos x + (cos x)^2 = 0
1 + 2sin x cos x = 0
1 + sin 2x = 0
sin 2x = -1
2x = -90
x = -45
2sin x - sin x = 3cos x - 4cos x
sin x = -cos x
sin x + cos x = 0
(sin x + cos x)^2 = 0
(sin x)^2 + 2sin x cos x + (cos x)^2 = 0
1 + 2sin x cos x = 0
1 + sin 2x = 0
sin 2x = -1
2x = -90
x = -45
2008-03-12 3:21 am
係咩程度
如果最容易應系下:
2sin x 4cos x = sin x 3cos x
2sin x - sin x = 3cos x - 4cos x
sin x = -1cos x
估下
2008-03-11 19:35:48 補充：
sorry i can't help you..
如果最容易應系下:
2sin x 4cos x = sin x 3cos x
2sin x - sin x = 3cos x - 4cos x
sin x = -1cos x
估下
2008-03-11 19:35:48 補充：
sorry i can't help you..
2008-03-12 3:13 am
..
收錄日期: 2021-04-23 18:56:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080311000051KK02103