It is important to note that there is a preference and a higher chance of successful handling of different tasks if one is acquainted with many theorems, such as Menelaus' Theorem
, Ceva's Theorem, Pascal's Theorem and others, which not each student and even teacher knows.
We described about generalizations of Menelaus' theorem to polygons and polyhedrons, and about backward generalization, from polyhedrons to polygons in chapter 3.
Also in chapter 3, since Menelaus' theorem is based on measurements of the line segments.
This equation is employed as our generalization of Menelaus' Theorem at polygons.
The idea of "cycle" takes central role in discovery of tetrahedral Menelaus' theorem.
This equation is what we will now say Menelaus' theorem for tetrahedrons.