Question 316948
The general equation for a circle centered at (h,k) with a radius R is:
{{{(x-h)^2+(y-k)^2=R^2}}}
or more usefully,
{{{(h-x)^2+(y-k)^2=R^2}}}

J:{{{(h+6)^2+(k-0)^2=R^2}}}
K:{{{(h+3)^2+(k-3)^2=R^2}}}
L:{{{(h-0)^2+(k-0)^2=R^2}}}
From the L equation,
{{{h^2+k^2=R^2}}}
From the J equation,
{{{(h+6)^2+k^2=R^2}}}
Equate those two,
{{{h^2+k^2=(h+6)^2+k^2}}}
{{{h^2=(h+6)^2}}}
{{{h^2=h^2+12h+36}}}
{{{12h+36=0}}}
{{{highlight(h=-3)}}}
From the K equation,
{{{(k-3)^2=R^2}}}
From the L equation,
{{{9+k^2=R^2}}}
Equate those two,
{{{9+k^2=k^2-6k+9}}}
{{{-6k=0}}}
{{{highlight(k=0)}}}
Finally using L,
{{{9+0=R^2}}}
{{{highlight(R^2=9)}}}
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{{{highlight_green((x+3)^2+y^2=9)}}}