Answer:
[tex]r=11[/tex]
Step-by-step explanation:
The equation of a circle is commonly denoted as:
[tex](x-h)^2+(y-k)^2=r^2[/tex], where [tex](h, k)[/tex] is the center of the circle.
This equation is already written in that format, therefore:
[tex]r^2=121,\\r=\fbox{$11$}[/tex],
