Jawabanmu

2014-04-01T20:01:04+07:00
2 sin x cos x = cos x
2 sin x cos x - cos x = 0
cos x (2 sin x - 1) = 0

cos x =0
      x = 90
      x = 270

2sin x -1 = 0
2sin x = 1
sin x = 1/2
     x= 30
    x = 150
1 3 1