CHCalcHandbook

General Polygon — From Vertex Coordinates

Section Properties · Polygon by Coordinates (shoelace) · A, C, I, S, r, Ixy, principal axes, Z
1

Geometry

One vertex per line: x, y (counter-clockwise). Further blocks separated by a blank line are treated as holes
The shoelace (Gauss) formulas give the exact area, centroid and second moments of the closed polygon. Curved edges are approximated with a sufficient number of vertices. Vertex order does not matter (the sign is corrected automatically).
2

Geometric properties

Area, centroid, moment of inertia, elastic section modulus, radius of gyration
3

Plastic modulus and torsion

Zx, Zy, shape factor, J
4

Principal axes

Ixy, θ, I₁, I₂