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I need math help....

I need math help....

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Old 02-21-2011, 06:18 PM
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I am a novice at pattern drawing, so please excuse me if that shows in this post. :?

I drew a pattern. It contains 68 triangles. I thought I would just cut 17 squares and cut those squares into 4 triangles each.

The end triangle (with seam allowance) needs to measure 2.25inx2.25inx4.25in. I thought cutting a 4.5in square would get me that. Instead I get a 3.5inx3.5inx4.5in triangle.

I looked up some information on square diagonals and I am realizing that I might not be able to do the easy way of starting with a square and cutting it down to 4 triangles.

So, how do I easily cut a 2.25x2.25.4.25 triangle? I tried to just cut one and I can't figure it out. I think my frustration is getting in my way of thinking clearly. I have a 6in x 24in ruler, a 3.5in x 24 in ruler and a 10.5in square ruler at my disposal. I could go buy another ruler, if recommended, tomorrow.

Thanks. I hope I'm making sense.
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Old 02-21-2011, 06:22 PM
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I'm only writing this all out because you say you're a novice.


Are you trying to make a HST (Half Square Triangle block)? Which is a square made up of 2 triangles, split diagonally between 2 fabrics?

Or QST (Quarter Square Triangle block), which is a square, cut twice diagonally?

And do you want the "finished block" to be 2 inches?
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Old 02-21-2011, 06:23 PM
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Can you post a picture of the pattern? For the triangles, are they right triangles with 2.25" legs and a 4.25" hypotenuse?
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Old 02-21-2011, 06:24 PM
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I'm only writing this all out because you say you're a novice.


Are you trying to make a HST (Half Square Triangle) block? Which is a square made up of 2 triangles, split diagonally between 2 fabrics?

Or QST (Quarter Square Triangles).

Do you want the "finished block" to be 2 inches?

Can you post a picture of the pattern? You'd get more direct answers that way.


And if you're going to be dealing with smaller sizes like you listed, it would be helpful to get a smaller ruler, maybe a 6" square, or something around that size.

It is very cumbersome to be dealing with so "extra" ruler. Your ruler collection will most certainly grow in the future. ;-)
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Old 02-21-2011, 06:29 PM
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Quarter Square Triangles

I want the triangle to measure 2.25x2.25x4.25 before I sew it to a rectangle that is part of the drawn pattern. The finished triangle will be 2x2x4.

I thought the easy way would be to cut big squares and then cut the square on the diagonal and then cut those two squares in half and that I would end up with 4 wonderfully lovely 2.25x2.25x4.25 triangles.

Now I just want to cut the triangles the right size. The initial square isn't really necessary. My mind is so stuck, I can't figure out how to get a 2.25x2.25x4.25 triangle.

I probably should draw a picture of what I'm doing, it would probably make more sense.
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Old 02-21-2011, 06:31 PM
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ok if you have two 2.25" legs on a right triangle, there is no way to make the 3rd side 4.25". It would be about 3.25".

If you can post a pic of the blocks I think it would be easier to help. I have no clue what kind of triangle you're wanting to make.
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Old 02-21-2011, 06:33 PM
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This is a pretty detailed how-to make HST's. I think you should read it first to get an idea of the most common method. The beauty of this method is NOT having to deal with any actual triangles and bias edges.

http://quilting.about.com/od/quickpi...squaretria.htm

Generally the math used is to add 7/8" to the finished size.
So if you wanted 2" HST finished, you add 1/2" for the seam allowance, and then 3/8" for the angle.

I prefer to cut the squares adding an inch or more to the finished size. So let's say 3 - 3.25" squares. Then make the HST and trim them down to the actual size. I find it makes a more accurate block, without having to bother with a 7/8" measurement. Also, if you make a slight error in the cutting, the square still wouldn't be the right size.

Others may have different opinions.
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Old 02-21-2011, 06:34 PM
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It's not possible to make 2.25 x 2.25 x 4.25 triangle. The two short sides combined HAVE to be bigger (more than .25" bigger for sure) than the third side.
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Old 02-21-2011, 06:37 PM
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Oh lord, I feel like a fool. No harm in learning right?!?! ;)

Here is what I'm attempting to do. So, I need to play with the pattern more. I want to make a chain of these rectangles and triangles. This is what I had drawn on graph paper and was trying to transfer measurements to fabric.

The picture is not to size, just a quick run up.
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Old 02-21-2011, 06:37 PM
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How about making a square exactly the size of the narrow side of the rectangle? Draw a pencil line diagonally from one corner to the other. Place the square right sides together over the end of the rectangle matching the cut edges. Sew on the diagonal line and trim 1/4 inch from the stitching line. Now the rectangle should have a half-square triangle that finishes off the rectangle! Hope that is what you are wanting. Happy quilting! :)
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