The equation of the circle can be determined as follow:
If you have the center in the point (0,0)
and r = 12
You use the next formula:
[tex]d=\sqrt[]{(x_2-x_1)^2+(y_2-y_1)^2}[/tex]Where
the d is equal to the r
x1 and y1= (0,0) (the center point)
x2 and y2 = (x,y)
Then we have:
[tex]r=\sqrt[]{(x_{}-0)^2+(y_{}-0)^2}[/tex][tex]r^2=(\sqrt[]{(x_{}-0)^2+(y_{}-0)^2}^{})^2[/tex][tex]r^2=(x_{}-0)^2+(y_{}-0)^2[/tex]The equation of the circle is:[tex]r^2=(x_{}-0)^2+(y_{}-0)^2[/tex]