Π: z = 0
A = PointIn(Π)
B = PointIn(Π)
C = Point(Circle[Midpoint[A, B], (Distance[A, B] * sqrt(3) / 2), Segment[A, B]])
a, D, faceABC, faceACD, faceABD, faceBCD, arêteAC, arêteAB, arêteBC, arêteAD, arêteCD, arêteBD = Tetrahedron(A, B, C)
E = Point(arêteBD)
F = PointIn(faceACD)
f = Line(E, F)
G = Intersect(f, Π)
p = Plane(B, D, F)
H = Intersect(arêteAC, p)
g = Line(G, H)