B = (5, -1)
A = (1, -1)
AB = Vector(A, B)
a = 4 (slider from -5 to 5, step 0.1)
b = 4 (slider from -5 to 5, step 0.1)
k = 1 (slider from -5 to 5, step 0.1)
ABe2: AB * AB
FABi: k * a * b / ABe2
ABu = UnitVector(AB)
fBAlibero: FABi * ABu
FBA = Vector(B, B + fBAlibero)
FAB = Vector(A, A - fBAlibero)
C = (4, 4)
c = 5 (slider from -5 to 5, step 0.1)
AC = Vector(A, C)
ACe2: AC * AC
FACi: k * a * c / ACe2
FCA = Vector(C, C + FACi * UnitVector[AC])