Question

Given the unit circle what is the value for y

Answer 1

see the attached figure below to better understand the problem

Remember that in a unit circle the radius r=1

so

Applying the Pythagorean Theorem in the right triangle

$1^2=(\frac{1}{2})^2+y^2$

Solve for y

$y^2=1-(\frac{1}{4})$$\begin{gathered} y^2=\frac{3}{4} \\ y=\frac{\sqrt[]{3}}{2} \\ \end{gathered}$