Origami maths part 1) a model can be correctly proportioned by dividing the initial square into rational fractions e.g. by reserving 2/7 of a paper for a head, the head will be the correct size after folding. Or as shown here, an extra column can be added to a 12x12 grid to give a crab body some width, resulting in a 13x13 grid.
This creates the problem, how can one divide a paper into any given rational fraction? This can be accomplished with approximations and a ruler, but a more pure method is to use folds to construct the fraction. Two techniques for doing just that are shown here: diagonal division (pictures 2,3) and Haga's technique (picture 4). If you want to learn more about the mathematics and more techniques, see the article Origami Constructions by Robert Lang (http://www.langorigami.com/article/huzita-justin-axioms) Crab by Robert Lang, folded by me
Rectangle 13:8, Kraft paper
CP drawn by me, not all centre folds are shown #origami #origamiart #crab #maths #geometry