Answer:
y = (√7)/4
Explanation:
The equation of the unit circle is ...
x^2 +y^2 = 1
Putting the given value in for x, we can find y to be ...
(-3/4)^2 +y^2 = 1
y^2 = 1 -(-3/4)^2 = 1 -9/16 = 7/16 . . . . . subtract 9/16
y = √(7/16) . . . . . . . . . . . take the square root; y > 0 here
y = (√7)/4