Write the equation in standard form of a circle with center (h,k) and radius r: \(\displaystyle{\left({x}−{h}\right)}^{{2}}+{\left({y}−{k}\right)}^{{2}}={r}^{{2}}\)

Isolate the variable terms and group them: \(\displaystyle{x}^{{2}}−{16}{x}+{y}^{{2}}−{8}{y}={1}\)

\(\displaystyle{\left({x}^{2}−{16}{x}\right)}+{\left({y}^{{2}}−{8}{y}\right)}={1}\)

Complete the square:

\(\displaystyle{\left({x}^{{2}}−{16}{x}+{64}\right)}+{\left({y}^{{2}}−{8}{y}+{16}\right)}={1}+{64}+{16}\)

\(\displaystyle{\left({x}−{8}\right)}^{{2}}+{\left({y}−{4}\right)}{2}={81}\)

or

\(\displaystyle{\left({x}−{8}\right)}^{{2}}+{\left({y}−{4}\right)}{2}={9}^{{2}}\)

So, the center is (8,4) and radius is 9.