Answer:
y = (√3)/2
Explanation:
The unit circle has equation ...
x^2 +y^2 = 1
For x = 1/2, the value of y can be found to be ...
(1/2)^2 +y^2 = 1
y^2 = 1 - 1/4 = 3/4 . . . . . subtract 1/4
y = √(3/4) . . . . . . . . . . take the square root (y > 0 here)
y = (√3)/2