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Originally Posted by k_jupiter
(Post 7238241)
The formula is A squared plus B squared = the square root of the diagonal.
Tate |
I'm puzzled you know the diagonal length.
usually I know the length of the sides then can work from there size of block and how many. You can try different sizes of block which will generate different number of blocks. far easier than playing with Pythagarus |
Hate to be picky, but I was a math teacher for 28 years. The formula is A squared plus B squared = the diagonal squared. Take the square root of the sum to find the length of the diagonal.
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A squared + B squared = C squared. C is the measurement from corner to corner. In this case C=38. Since we're dealing with a square, A = B.
Therefore, 2 * (A * A) = (38 * 38). or 2*(A*A) = 1444. If you divide 1444 by 2, you'll get the value for A*A. A * A = 722. Now use the square root function on your calculator to get 26.87. I would round up to 28 or 29 to allow for seam allowances and the fudge factor. As someone else said it's easier to trim fabric than add to it once it's cut. |
I am just "pyth-ed".
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Originally Posted by k_jupiter
(Post 7238241)
If the 38 inches is the diagonal of your square (which is how I read it) the sides of the square need to be 26 7/8 inch.
The formula is A squared plus B squared = the square root of the diagonal. Or, as this is a square, 2 times A times A (because A = B) = the square root of the diagonal. So if you take your 38 inches and square it (multiply 38 times 38) then divide that by 2 you have the number that if you find what multiplies itself to get that number that is the length of the side. Called the square root. Do not try this without a calculator or spread sheet. Confused? I don't blame you. It's harder to describe than to do. The number is 26 7/8 in this case. tim in san jose |
Originally Posted by Onebyone
(Post 7238273)
Why wouldn't just measuring down one side of the diagonal work? Wouldn't that give you 26 7/8 size square?
This is so funny! It's like can't see the forest for the trees. |
Originally Posted by faykilgore
(Post 7238536)
Pythagorean theorem. I knew there was a name for that formula!
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Math is certainly not my thing. I tend to shy away from projects needing me to do much figuring
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buy basic graph paper (quilters paper is great, but regular graph paper works fine and is cheaper). use 4 squares to an inch - this will make each square 1/4", so easy to add in seam allowances. With a PENCIL, start putting in the blocks you know about. Then it is easy to figure out how big your other blocks need to be. If you get an odd shape or still have problems figuring size, cut out your block and lay in on the paper and add your seam allowances. this will let you see the sizes without doing a lot of math. Little difficult to explain but as you try one that you already know, it will make sense.
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