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The course "General Equation of Circle" is a compulsory course in senior high school mathematics of Jiangsu Education Press.
Let the equation of the garden be: x? +y? +Dx+Ey+F=0...........①;

Substitute the coordinates of A and B: 20+4d+2e+f = 0...②; 10-D+3E+F=0.........③;

Let x=0 in the formula (1), then there is y? +Ey+F = 0; Let the intercept of the garden on the y axis be y? ,y? ; So y? +y? =-E.......④;

Let y=0 in the formula (1), then there is x? +Dx+F = 0; Let the intercept of the garden on the x axis be x? ,x? ; So x? +x? =-D......⑤;

Known x? +x? +y? +y? =-D-E = 2; That is e =-d-2; Substituting it into equation ②, we can get: 16+2D+F = 0...⑥.

And then substitute into formula ③, Simplifying: 4-4d+f = 0 ...................................................................................................................................................... ⑥-⑥:12+6d = 0, so d =-2; e = 0; f =- 12;

The equation of hometown is: x? +y? -2x- 12 = 0; That is (x- 1)? +y? = 13;