Sélectionner t dans la fenêtre Algèbre 
puis déplacer K à l'aide des flèches du clavier.

A = (14.611035265550697, -2.4582822505837445, 0)
B = (13.033093274465628, -0.16521881628356017, 0)
C = (7.918696819297779, -5.007730931847686, 0)
poly1, c, a, b = Polygon(A, B, C)
D = (9.148185371342457, -0.8107756671782663, 4.810083531591122)
d, faceABD, faceBCD, faceACD, arêteAD, arêteBD, arêteCD = Pyramid(poly1, D)
t = 1.7 (slider from -2 to 2, step 0.05)
e = Line(C, D)
f = Line(A, B)
M = Point(A, Vector[(t * Vector[A, B])])
N = Point(C, Vector[(t * Vector[C, D])])
K = Midpoint(M, N)
J = Midpoint(B, D)
I = Midpoint(A, C)
g = Segment(N, M)