In A Survey of Geometry by Howard Eves on pg 26 and 27 Eves defines a Parabola and lists several theorems.
Theorem 6 staes: If the tangent of the parabola at point P cuts the axis in point T and the normal to the parabola at P cuts the axis in point N, then TF = FP, TV = VM, and FN = half the latus rectum.
Where F is the focus, V the vertex, and M the foot of the perpendicular from P on the axis.
I somehow get MN = half the latus rectum if I am reading all definitions correctly, and cannot get FN = half the latus rectum using Cabri II. Is this an error in the book or have I made some error in my definitions?