\frac{\overline{ZA}}{\overline{ZA'}} = 
\frac{\overline{ZB}}{\overline{ZB'}} = 
\frac{\overline{AB}}{\overline{A'B'}}

Z = (-2.82, 0.94)
A = (4.14, 1.54)
B = (4.72, 4.5)
s1 = Ray(Z, A)
s2 = Ray(Z, B)
h = Line(B, A)
A' = Point(s1)
g = Line(A', h)
B' = Intersect(s2, g)