Mova o ponto C para definir a elipse.
Mova o ponto D para verificar a propriedade

A = Point(xAxis)
B = Point(xAxis)
C = (2.059902439024395, 2.471970731707318)
c = Ellipse(A, B, C)
D = Point(c)
a_1 = PolyLine(A, D, B)
texto2: " \sqrt{\left(x-\alpha\right){}^{2}+ y^{2}} + \sqrt{\left(x+\alpha\right){}^{2}+ y^{2}} = d =  " + (LaTeX[a_1]) + " "
E = Intersect(c, xAxis, 1)
G = Intersect(xAxis, yAxis)
a = Segment(E, G)
F = Intersect(c, yAxis, 2)
b = Segment(G, F)
texto3: "a= " + a + " e b= " + b + " (semi-eixos da elipse)"