Answer
$(-0.5,0.866),(-0.5,-0.866)$
Work Step by Step
The line $x=-\frac{1}{2}$ intersects the circle $x^2+y^2=1$ at $(-0.5,0.866)\,$and$\,(-0.5,-0.866)$ as can be seen from the figure.
The solution can also be obtained analytically by substituting $x=-\frac{1}{2}$ in the equation $x^2+y^2=1$ and solving for $y$ $$y^2 = 1-x^2$$ $$y = \pm \sqrt{1-x^2} = \pm \sqrt{1-(-0.5)^2} = \pm \sqrt{\frac{3}{4}}$$ $$\therefore y = \pm \frac{\sqrt{3}}{2} \approx \pm 0.8660$$ $\therefore $ The coordinates are $(-0.5,0.866)$and$(-0.5,-0.866)$.