Which of the following could not be points on the unit circle?
a.(0.8, -0.6)
/3,√ 5/3)
c.(√ 3/2, 1/3)
d.(1,1)

A. √(0.8^2) + (0.6^2) = √1 = 1 => OK

b.(-2/3,√ 5/3) = √(-2/3)^2 + 5/9) = √(4/9 +5/9) = √1 = 1 => OK

c.(√ 3/2, 1/3) = √(3/4 + 1/9) < 1 => it is inside the unit circle

d.(1,1) = √(1 + 1) = √2 > 1 => NO. This point is beyond the limits of the unit circle.