Answer
Center of the circle is $\left( 0,0 \right)$ and radius is $r=\sqrt{20}$
Work Step by Step
Standard equation of the circle is:
${{\left( x-h \right)}^{2}}+{{\left( y-k \right)}^{2}}={{r}^{2}}$ (equation -1)
And equation of the circle is ${{x}^{2}}+{{y}^{2}}=20$ (equation - 2)
Now compare both the equations.
$\begin{align}
& {{\left( x-0 \right)}^{2}}+{{\left( y-0 \right)}^{2}}=20 \\
& {{\left( x-0 \right)}^{2}}+{{\left( y-0 \right)}^{2}}=\sqrt{20} \\
\end{align}$
Center coordinate of the circle is $\left( h=0,k=0 \right)$.
And radius of the circle is $r=\sqrt{20}$.
To graph, we plot the points $\left( 0,4.472 \right)$, $\left( 0,-4.472 \right)$, $\left( -4.472,0 \right)$, and $\left( 4.472,0 \right)$ which are, respectively, $\sqrt{20}$ units above, below, left and right of $\left( 0,0 \right)$
