Z = (0, 0)
a = 1.9 (slider from 0 to 3, step 0.1)
A = (0.3555785938369323, 0.9769574487030988)
B = (1.8543533141669637, -0.5107643385604265)
b = Line(A, B)
P = Point(b)
c = Ray(Z, P)
abstandZP = Distance(Z, P)
TextZP: "\overline{" + (Name[Z]) + (Name[P]) + "} \, = \, " + abstandZP
d = Circle(Z, a + Distance[Z, P])
P' = Intersect(d, c)
Ortslinie1 = Locus(P', P)