Menelaus' Theorem
This article is a stub. Help us out by expanding it.
Menelaus' Theorem deals with the collinearity of points on each of the three sides (extended when necessary) of a triangle. It is named for Menelaus of Alexandria.
Statement
A necessary and sufficient condition for points 
on the respective side lines 
of a triangle 
to be collinear is that
where all segments in the formula are directed segments.
