Respuesta :

Hippalectryon
[tex]x^2+y^2=9\Leftrightarrow (x-0)^2+(y-0)^2=3^2[/tex] hence the center is (0,0) and the radius is 3
konrad509
[tex](x-x_1)^2+(y-y_1)^2=r^2\\ \text{center}=(x_1,y_1)\\\\ x^2+y^2=9\\ (x-0)^2+(y-0)^2=9\\ \text{center}=(0,0)\\ r=\sqrt9=3 [/tex]