P   \; :  \; \;   y= \frac{ 1 }{ 4} x² \; 

k = -4.3 (slider from -8 to 8, step 0.1)
M: (k, 0.25 k^(2))
T, b = Tangent(M, P)
N = OrthogonalLine(M, T)
a = Line(M, yAxis)
c = Mirror(a, N)
A = Point(a)
I = Ray(M, A)
B = Point(c)
R_1 = Ray(M, B)
C = Intersect(P, R_1, 2)
R = Segment(M, C)

Tool: rayons
Input: P, M
Output: d, e

T, b = Tangent(M, P)
N = OrthogonalLine(M, T)
a = Line(M, yAxis)
c = Mirror(a, N)
A = Point(a)
d = Ray(M, A)
B = Point(c)
R = Ray(M, B)
C = Intersect(P, R, 2)
e = Segment(M, C)