about sin cos tan

2009-04-23 3:31 am
1-2cos(x+10)=0

sin3x=cos45.tan45

(tan2x-sin60).tan30=cos 60

回答 (1)

2009-04-23 6:27 am
✔ 最佳答案

題目並不清楚要計算些甚麼。
假設是要計算 x ,而 0 ≤ x ≤ 360。


1 - 2cos(x + 10o) = 0
2cos(x + 10o) = 1
cos(x + 10o) = 1/2
x + 10o = 60o, 360o - 60o
x = 50o, 290o


sin3x = cos45o•tan45o
sin3x = cos45o•(sin45o/cos45o)
sin3x = sin45o
3x = 45o, 180o-45o, 360o+45o, 540o-45o, 720o+45o, 900o-45o
x = 15o, 45o, 135o, 165o, 255o, 285o


(tan2x - sin60o)tan30o = cos60o
[tan2x - (√3)/2)](1/√3) = 1/2
tan2x - (√3)/2 = (√3)/2
tan2x = (√3)/2 + (√3)/2
tan2x = √3
2x = 60o, 180o+60o, 360o+60o, 540o+60o
x = 30o, 120o, 210o, 300o
=


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