Saturday, September 27, 2008

Check My Math

I was thinking about triangles last night and this morning (and the day before, and the day before that, and . . . but you get the idea). Triangles inevitably lead to geometry, more specifically, to Pythagoras. Let's review that basic tenet, the Pythagorean Theorem, the formula you need to find the length of the sides of any given triangle:

A-squared + B-squared = C-squared (sorry, no mathematical notation on my keyboard).

I'm trying to produce an equilateral triangle here, yes? So my A and B are going to be equal.

If my C = 26 inches/130 rows, what does my A have to be? The answer is not happy-making.

C-squared in inches = 676 = 2(A=squared)
A-squared = 676/2 = 338
The square root of 338 is 18.384477. Let's call it 18.4.
18.4 * 5 (my row gauge) = 92.


C-squared in rows = 16900 = 2(A-squared)
A-squared = 16900/2 = 8450
The square root of 8450 is 91.923881. Let's call it 92 (again).


Each leg of my triangle needs to be 92 rows long. I have 130 rows to work with along the hypotenuse. I need 184 rows along the edge of a piece that's 130 rows long. I suspect that I have found the source of my inability to get the piece up to 12.5 inches. It's not the body of the knitting, it's the edges. The sides can't stretch far enough.

Meh. I wonder if I have time to knit another sweater for afghans for Afghans. The deadline is October 14, and I don't have any bulky yarn in my stash, so probably not. Which leaves me with figuring out how to add 54 rows to the border. So, do I want short rows? Huh. That's 27 pairs, since I have to go out and back again. One at the apex means 13 along each 65 row side. One pair about every 5 rows. Would that actually work? And I could probably stop messing around with all those increases. Hmm.

No wonder I hate math. It's so reality based.

2 comments:

Cathy said...

You may hate math, but at least you know what the Pythagorean Theorem is. I salute you for even trying to figure this out.

I'm using my green yarn to make a vest for a4A. The vest is working up nicely & (fingers crossed) will be done tonight...no, make that tomorrow night....Monday at the latest.

Thanks again. Cathy

cheesehead with sticks said...

Oh my - once you started in with all those numbers your post turned to greek. Amazing that you are also bilingual!

Not that I don't get it, but I choose not to get it :) (I had a few traumatic years in college for engineering! Ignoring math is my poor coping skill - ha!)

So, um, all that is left to say is Good Luck!