Pappus's theoremPappussTheorem2002-02-20 23:06:382003-08-19 15:52:05Theorem\usepackage{graphicx}
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Let $A,B,C$ be points on a line (not necessarily in that order) and let $D,E,F$ points on another line (not necessarily in that order). Then the intersection points of $AD$ with $FC$, $DB$with $CE$ and $BF$ with $EA$ are collinear.
This is a special case of Pascal's mystic hexagram.
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