Ceva's Theorem

Revision as of 17:24, 18 June 2006 by SnowStorm (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Statement

A necessary and sufficient condition for AD, BE, CF, where D, E, and F are points of the respective side lines BC, CA, AB of a triangle ABC, to be concurrent is that


$BD * CE * AF = +DC * EA * FB$


where all segments in the formula are directed segments.

Example

Suppose AB, AC, and BC have lengths 13, 14, and 15. If AF:FB = 2:5 and CE:EA = 5:8. If BD = x and DC = y, then 10x = 40y, and x + y = 15. From this, we find x = 12 and y = 3.

Invalid username
Login to AoPS