Shoestring
Revision as of 21:10, 22 March 2008 by Stevenmeow (talk | contribs)
This formula finds the area of any 2-D figure whose coordinates of the vertices are known and the order in which the vertices are connected given coordinates (in order) (A,B) (C,D) ... You stack them vertically until you reach the first vertex make sure you list 1st vertex again at the bottom. For a quadrilateral, this step would look like
A B
C D
E F
G H
A B
Now you find cross products. First all the diaonally down to the left. This would mean BC, DE, FG, and HA. Then these are added. Then diagonally to the right. This would mean AD, CF, EH, and GB. These are also added. the area is half of the positive difference between the sums
