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# Menelaus' theorem ( transversal line passes inside triangle )

## Description

Menelaus’ theorem, named for Menelaus of Alexandria, is a theorem about triangles in plane geometry. Given a triangle ABC, and a transversal line that crosses BC, AC and AB at points D, E and F respectively, with D, E, and F distinct from A, B and C, then there is a relation between the segments.The equation uses signed lengths of segments, in other words the length AB is taken to be positive or negative according to whether A is to the left or right of B in some fixed orientation of the line. For example, AF/FB is defined as having positive value when F is between A and B and negative otherwise.

Related formulas

## Variables

 AF Segment on AB side of the triangle (dimensionless) FB Other Segment on AB side of the triangle (dimensionless) BD Segment on BC side of the triangle (dimensionless) DC Other Segment on BC side of the triangle (dimensionless) CE Segment on AC side of the triangle (dimensionless) EA Other Segment on AC side of the triangle (dimensionless)