Directrice

Axes

\vec{j}

\vec{i}

a = 0.5 (slider from 0.1 to 1, step 0.1)
P = Function(a x^(2), -2, 2)
A = Point(P)
T = Tangent(A, P)
d = Line(A, yAxis)
B = Point(d)
b = OrthogonalLine(A, T)
e = OrthogonalLine(B, b)
C = Intersect(b, e)
f = Circle(C, B)
D = Intersect(f, e, 2)
g = Ray(A, D)
h = Ray(A, B)
S = (0, 0)
F: (0, 1 / (4 a))
i = Segment(S, F)
T1: "y=" + a + "x²"
c: y = -1 / (4 a)
j = OrthogonalLine(A, c)
H = Intersect(c, j)
k = Segment(A, H)
l = Distance(A, F)
T2: "AF=" + l
T3: "AH=" + k
m = false
n = false
p = If(n ≟ true, xAxis)
q = If(n ≟ true, yAxis)
I = (1, 0)
J = (0, 1)
O = (0, 0)
u = Vector(O, I)
v = Vector(O, J)