The geometric centroid of a quadrilateral lamina is the center of its Wittenbauer's parallelogram.
Wittenbauer's Theorem
See also
Geometric Centroid, Lamina, Quadrilateral, Wittenbauer's ParallelogramExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Wittenbauer's Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/WittenbauersTheorem.html