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PDN Theorem For Quadrilateral As Van Aubels Theorem.svg Diagram illustrating the fact that van Aubel's theorem is special case of PetrDouglasNeumann theorem Krishnachandranvn talk created this work entirely by myself May UTC Krishnachandranvn talk Krishnachandranvn en Cczero Original upload log en PDNTheoremForQuadrilateralAsVanAubelsTheorem