// Pour les paraboles par 3 points

a

(x(A)*(y(C)-y(B))-x(B)*y(C)+y(B)*x(C)+y(A)*(x(B)-x(C)))/(x(A)*(x(C)^2-x(B)^2)-x(B)*x(C)^2+x(B)^2*x(C)+x(A)^2*(x(B)-x(C)))

b

-(x(A)^2*(y(C)-y(B))-x(B)^2*y(C)+y(B)*x(C)^2+y(A)*(x(B)^2-x(C)^2))/(x(A)*(x(C)^2-x(B)^2)-x(B)*x(C)^2+x(B)^2*x(C)+x(A)^2*(x(B)-x(C)))

c

(x(A)*(y(B)*x(C)^2-x(B)^2*y(C))+x(A)^2*(x(B)*y(C)-y(B)*x(C))+y(A)*(x(B)^2*x(C)-x(B)*x(C)^2))/(x(A)*(x(C)^2-x(B)^2)-x(B)*x(C)^2+x(B)^2*x(C)+x(A)^2*(x(B)-x(C)))