Answer:
Center: (9,3)
Radius: 9 units
Step-by-step explanation:
[tex]x^{2} -y^{2} -18x-6y+9=0[/tex]
[tex]x^{2} -18x+81+y^{2} -6y+9=-9+81+9[/tex]
[tex](x-9)^{2} +(y-3)^{2} =81[/tex]
Center: (9,3)
[tex]r^{2} =81[/tex] → [tex]r=9[/tex]
Radius : 9 units
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