Hi all, i am interested in finding out the Geometrical properties of an arbitrary section, which means 2D area. Rather than having to perform manual calculations everytime, i am trying to write a program to help me with this. There is a problem however. I cannot seem to find the appropriate mathematical expressions to help me obtain the following : (1) Area (2) Centroid (3) Moment of Inertia To help make the program easier to write, i have decided that all lines drawn are straight lines, therefore eliminating the tedious curves. Hence i can easily calculate the length of each lines and sum them up to obtain the perimeter. This is possible, because i have all the co-ordinate points. Now, what about area? I have tried using the Green's Theorem for calculations, but i am not sure whether it works for sections which have a large number of co-ordinate points. Also the centroid can also be worked out using Green's Theorem, and once again, it is not known whether it works for arbitrary co-ordinates. Does it have any limitations? Can anyone help explain to me whether Green's Theorem is good for this application? Or does anyone have a clearer or better algorithm which i can use? Thanks in advance .... it's rather urgent..