from sin(180-x) = sin(x)
sin(150) = sin(180-30) = sin(30)
sin(120) = sin(180-60) = sin(60)
from cos(360-x) = cos(x)
cos(300) = cos(360-60) = cos(60)
cos(210) = cos(360-150) = cos(150)
from cos(180-x) = -cos(x)
cos(210) = cos(150) = cos(180-30) = -cos(30)
