Jawabanmu

2014-03-12T18:08:01+07:00
Cos2x = 1 - 2sin^2 x
1-2 sin^{2} x - sin x = 0
2 sin^{2} x + sin x -1= 0 
(2sin x - 1)(sin x +1)
sinx= 1/2 , sin = -1

sin x = 1/2
x = 30, 150

sin x = -1 
x=270
HP { 30,150, 270 }
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