Given cos(x) = -1/9 with cos(x/2) - (2/3) (2/3) (√5) /3 - (2√2) /3 180°. Find cos(x/2) - (2/3) (2/3) (√5) /3 - (2√2) /3.
a) -1/3
b) 2/3
c) 1/3
d) -2/3