This method is attributed to the French engineer Eduard Lill (1867).

The side-splitter theorem states: If a line parallel to one side of a triangle intersects the other two sides in different points, it divides the sides in the same ratio [2. p. 354].

References

[1] D. Kurepa, Higher Algebra (in Croatian), Zagreb: Skolska knjiga, 1965 pp. 1071–1073.

[2] H. R. Jacobs, Geometry (2nd ed.), New York: W. H. Freeman and Company, 1987.