a*x+b*y+c=0 (x-a)^2+(y-b)^2=r^2

$$left(- a + xright)^{2} + left(- b + yright)^{2} = r^{2}$$

$$b_{1} = – frac{1}{x^{2} + y^{2}} left(c y + x sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=
$$- frac{1}{x^{2} + y^{2}} left(c y + x sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=

-(c*y + x*(-c^2 – x^4 – y^4 + r^2*x^2 + r^2*y^2 – 2*c*x^2 – 2*c*y^2 – 2*x^2*y^2)^0.5)/(x^2 + y^2)

$$a_{1} = frac{1}{x^{2} + y^{2}} left(- c x + y sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=
$$frac{1}{x^{2} + y^{2}} left(- c x + y sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=

(y*(-c^2 – x^4 – y^4 + r^2*x^2 + r^2*y^2 – 2*c*x^2 – 2*c*y^2 – 2*x^2*y^2)^0.5 – c*x)/(x^2 + y^2)

$$b_{2} = frac{1}{x^{2} + y^{2}} left(- c y + x sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=
$$frac{1}{x^{2} + y^{2}} left(- c y + x sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=

(x*(-c^2 – x^4 – y^4 + r^2*x^2 + r^2*y^2 – 2*c*x^2 – 2*c*y^2 – 2*x^2*y^2)^0.5 – c*y)/(x^2 + y^2)

$$a_{2} = – frac{1}{x^{2} + y^{2}} left(c x + y sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=
$$- frac{1}{x^{2} + y^{2}} left(c x + y sqrt{- c^{2} – 2 c x^{2} – 2 c y^{2} + r^{2} x^{2} + r^{2} y^{2} – x^{4} – 2 x^{2} y^{2} – y^{4}}right)$$
=

-(c*x + y*(-c^2 – x^4 – y^4 + r^2*x^2 + r^2*y^2 – 2*c*x^2 – 2*c*y^2 – 2*x^2*y^2)^0.5)/(x^2 + y^2)