There are several theorems that generally are known by the generic name "Pappus's Theorem." They include Pappus's centroid theorem, the Pappus chain, Pappus's harmonic theorem, and Pappus's hexagon theorem.
Pappus's Theorem
See also
Pappus's Centroid Theorem, Pappus's Harmonic Theorem, Pappus's Hexagon TheoremExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Pappus's Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PappussTheorem.html