Equations for different quadrants of a circle

Question

In the circle $x^2$ + $y^2$ = $a^2$, what's the general equation for the arcs in each of the quadrants?

Answer 1

Different Quadrants of circle $$x^2+y^2=a^2$$ can be represented by $$y=\sqrt{a^2-(\sqrt {x})^4}$$ $$y=\sqrt{a^2-(\sqrt {-x})^4}$$ $$y=-\sqrt{a^2-(\sqrt {x})^4}$$ $$y=-\sqrt{a^2-(\sqrt {-x})^4}$$ I guess you've understood the trick