Geometry of Crocheting: Simple Math for Simple Minds

With the craze of Angry Birds, comes the craze of real life reiterations of the game's characters. The other popular craze for the young, hipster crowd is crafting (eek! I said the dreaded c-word) including crocheting. I'm not usually into crafting and like to make the fine distinction between being crafty and being artsy-fartsy. I like to think, or at least have convinced myself, that creating the Angry Bird characters via crocheting falls under the artsy side of things.

Creating the yellow, triangular bird requires some long-lost geometry calculations. In order to accurately depict the bird, it must be made as a 3D triangle. 3-sides and 1-bottom piece. Each of the 4 pieces needs to be an equilateral triangle to fit together appropriately. Here is my word problem:

Assuming I begin with 30 stitches, how many rows will I need to crochet and by how many stitches will I need to decrease to make the sides of the triangle equal? Here's an equation that may help:

h (height) = a (length of one side) x √3/2 (This is a derivation from the pythagorean theorem)

a = 30 st (length of one side) x (√3/2)
h = 26

This doesn't sound quite right as you would guess you would end up with 30 rows for 30 stitches in length. Trust me, this formula works! That is what math is for dears. And who, besides me, ever said there were no real world applications of what you learn in math class? I chose to decrease each row by one stitch and then every 4 rows or so to decrease by 2 instead of by 1 and look where it got me: