Function defined by a relation in the form

*f*(

*x*) = \(\sqrt{{r}^{2} – {x}^{2}}\) or

*f*(

*x*) = − \(\sqrt{{r}^{2} – {x}^{2}}\) where

*r* is the radius of a circle centered on the origin point.

### Examples

Here is the graph of the function defined by the relation *f*(*x*) = \(\sqrt{{4} – {x}^{2}}\) :

Here is the graph of the function defined by the relation *f*(*x*) = − \(\sqrt{{4} – {x}^{2}}\) :