數學,急!!超急.......呢條數一定要超快計

2sin x + 4cos x = sin x + 3cos x, where 0<= x <=360
2sin 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

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

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..

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