Question 1191484
Three points; A(0,0), B(3,1) and C(5,7) lie on a circle. Find the equation of the circle. ​
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Step 1, find the equation of AB, then the equation of BC.
Step 2, find the perpendicular bisectors of AB and BC.
Step 3, find the intersection of the perp bisectors.  That's the center of the circle at (h,k).
Step 4, find the distance from the center to any of the 3 points given, that's the radius, r.
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Then {{{(x-h)^2 + (y-k)^2 = r^2}}}
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That's one way to do it.
I would use matrices.