# The expression whose vanishing guarantess that the symbolic
TouchCeLe1:=proc(C1,L1) local F:
F:=expand(subs(y=solve(L1,y),C1)):
numer(normal(4*coeff(F,x,2)*coeff(F,x,0)-coeff(F,x,1)^2)):
end:
# circle C1 and symbolic Line L1 touch
# it plugs the equation of the Line into the equation of the circle
and computes
#the discriminant