Answer:
A, C
Step-by-step explanation:
For a point to be on the unit circle, it must be a solution to ...
x² +y² = 1
__
The sums of squares of the x- and y-values are ...
A: 1² +1² = 2 . . . not on the circle
B: (-2/3)² +(√5/3)² = (4+5)/9 = 1
C: (√3/2)² +(-1/3)² = 3/4 +1/9 = 31/36 . . . not on the circle
D: 0.8² +(-0.6)² = .64 +.36 = 1
Points A and C do not lie on a unit circle.
