Exactly! I was busy making a sample to illustrate it for you.
Here are the two segments in question. They're both squared and are exactly the same size.
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After sewing together, you can see that the point doesn't go all the way to the corner. This will be your seam allowance when you sew a border to the top.
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An earlier poster had recommended a different method for assembling QSTs (Quarter-square triangles, which is what these are). I second that recommendation. When you sew triangles, you are dealing with lots and lots of bias edges. Using this method shown
here will help minimize distortions caused by handling and pressing those bias edges. Another tip for bias edges is to starch your fabric before you cut.