$x=-i\sqrt{y}\sqrt{y-4}+\frac{1}{2}$
$x=i\sqrt{y}\sqrt{y-4}+\frac{1}{2}$

$y=-\frac{\sqrt{15+4x-4x^{2}}}{2}+2$
$y=\frac{\sqrt{15+4x-4x^{2}}}{2}+2$

$x=-\sqrt{4y-y^{2}}+\frac{1}{2}$
$x=\sqrt{4y-y^{2}}+\frac{1}{2}\text{, }y\geq 0\text{ and }y\leq 4$

$y=-\frac{\sqrt{15+4x-4x^{2}}}{2}+2$
$y=\frac{\sqrt{15+4x-4x^{2}}}{2}+2\text{, }x\geq -\frac{3}{2}\text{ and }x\leq \frac{5}{2}$