Find the terminal point on the unit circle determined by 5pi/3 radians

See the attached figure to better understand the problem

step 1
convert radians to degrees
5pi/3 radians> 5*180°/3> 300°
300°> belong to the IV quadrant

step 2
find angle ∅
∅=360°-300°> ∅=60°> see the picture

step 3

find the coordinates of the terminal point
x=r*cos ∅
y=r*sin ∅
r=1 unit  (unit circle)

so
x=(1)*cos 60°> x=1/2
y=-(1)*sin 60°> y=-√3/2

the point is (1/2, -√3/2)

Answer is either b or c