smc

Let us think about this. We only know that he ends up $\sqrt{3}$ away from the origin. However, think about the locus of points $\sqrt{3}$ away from the origin, a circle. However, his path could end on any part of the circle below the $x-$axis, so therefore, the answer is $\boxed{\text{not uniquely determined}}.$ (Note: Another way to do this is using law of cosines, which yields two solutions for x.)