Jawabanmu

2014-05-25T00:00:24+07:00
F(x) = Cos²(x-π)
      = {Cos(x-π)}²
f'(x) = 2Cos(x-π)(-Sin(x-π)
       = -Sin2(x-π)
       = - Sin(2x - 2π)
f ' (π/6) = - Sin(π/3 - 6π/3)
             = - Sin(-5π/3)
             = Sin5π/3
             = Sin 300'
             = Sin(360' - 60')
             = - Sin 60'
             = - 1/2√3    (jawaban no 5)