Im a bit confused, are the values going to be the same on the unit circle for cos and sin, even though the radian is negative?
cos (-2pi/3) =
cos (2pi - 2pi/3) = cos ( [ 6pi - 2pi] / 3) = cos (4pi / 3) = cos(240°) = -1/2
And sine of the same angle = -√3 / 2
