Question 376200
{{{drawing(300,300,-14,3,-3,14,grid(1),
circle(-5,13,0.2),
circle(2,6,0.2),
circle(-12,6,0.2),
graph(300,300,-14,3,-3,14,0))}}}
Two ways to do it.
First way, the computationally intensive way is to use the general equation of a circle, {{{(x-h)^2+(y-k)^2=R^2}}}
Then use each of the points to get an equation in terms of {{{h}}},{{{k}}}, and {{{R}}}.
You'll get 3 equations in 3 unknowns.
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The second way is to recognize the the two left and right points are 2R away from each other and the top point is R units up from the center. 
{{{drawing(300,300,-14,3,-3,14,grid(1),
circle(-5,13,0.2),
circle(2,6,0.2),
circle(-12,6,0.2),
circle(-5,6,0.3),
blue(circle(-5,6,7)),
blue(line(2,6,-12,6)),
blue(line(-5,6,-5,13)),
graph(300,300,-14,3,-3,14,0))}}}
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{{{R=7}}}
({{{h}}},{{{k}}})=({{{-5}}},{{{6}}})
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{{{highlight((x+5)^2+(y-6)^2=49)}}}