am I smarter than a 5th grader (nooooooo!!!!!!)
06-26-2015, 05:50 PM
#11
Senior Member
Join Date: Nov 2011
Location: Cary, NC
Posts: 383
06-26-2015, 10:40 PM
#12
Super Member
Join Date: Jun 2010
Location: England Alton Towers
Posts: 6,673
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
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
06-27-2015, 07:05 AM
#14
Junior Member
Join Date: Aug 2010
Location: Massachusetts
Posts: 251
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.
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.
06-27-2015, 08:55 AM
#16
Super Member
Join Date: Jul 2010
Location: Central Willamette Valley, Oregon, USA
Posts: 7,695
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
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
06-27-2015, 10:56 AM
#20
Super Member
Join Date: Dec 2012
Posts: 1,857
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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