|AB|

|AB|

|A'B'|

Z = (-20, -39)
k = 3 (slider from 0.1 to 5, step 0.1)
A = (-20, -40)
B_1 = (40, -40)
f = Line(A, B_1)
a = 2 (slider from 0 to 10, step 0.5)
c = Circle(A, a)
C, B = Intersect(c, f)
g = Segment(A, B)
h = Ray(Z, A)
i = Ray(Z, B)
j = Segment(Z, A)
l = Segment(Z, B)
d = Circle(Z, (k * j))
e = Circle(Z, (k * l))
A', A'_1 = Intersect(d, h)
B', B'_1 = Intersect(e, i)
m = Segment(A', B')