Match the x-coordinates with their corresponding pairs of y-coordinates on the unit circle

y=+- square root 5 over 3
y=+- square root 7 over 3
y=+- 3 over 3
y=+- 2 square root 2 over 2

Equation of unit circle is:
 x² + y² = 1
we plug in the values of y to get the values of x.
 x² +√(5/3)² =1
x²=1- (5/3)
x²= -2/3
x=√(-2/3)
solve the rest by using the same technique and solve each value of y for x