and \(\sqrt {{g^2} + {f^2} - c}\) is the radius. Notice that for the circle to exist, \({g^2} + {f^2} - c\textgreater0\). Look at the following worked examples.

To find the equation of a circle when you know the radius and centre, use the formula \({(x - a)^2} + {(y - b)^2} = {r^2}\), where \((a,b)\) represents the centre of the circle, and \(r\) is the ...