Centroid Command

Centroid[ <Polygon> ]

Returns the centroid of the polygon.

Example:

Let A = (1, 4), B = (1, 1), C = (5, 1) and D = (5, 4) be the vertices of a polygon. Polygon[ A, B, C, D ] yields poly1 = 12. Centroid[ poly1 ] yields the centroid O = (3, 2.5).