Triangles?
 

Math ain't my strong suit. I have a pattern that calls for a 3 7/8" square cut diagonally once. Then it wants a 4 1/2" square cut diagonally twice. Does this sound right? Also where do you square this up? Use the 45 degree line? The triangles didn't measure quite right. The points didn't match even with a 1/4 seam allowance.

Anyone help? Please?

For HST you cut 7/8" larger than the finished size, and for QST you cut 1 1/4" larger. So the 3 7/8" square cut diagonally once would result in a 3" piece, and the 4 1/2" square would result in 3.25" finished. They probably want you to cut down the second piece, but then why not also have you make the first one 4" and cut it down?

Dunster is correct. Math IS my strong suit (most days). I'm a retired mathematics teacher. I, however, will almost always cut my squares larger and then trim down the HST or QST. You do need to figure half of your unfinished size to trim them down keeping proper proportions.

Logically, the sizes did look wrong.

There are 2 smaller triangles making a half triangle connected to one larger triangle to make a block. The 2 smaller triangles are cut from the 4 1/2" block. When you put that triangle next to the triangle cut from the 3 7/8" block, that 3 7/8" triangle is smaller. Would it be easier to stitch the triangles aligned on the center point and trim off the edges of the larger one after sewing the seam?

This is actually a border - sewing by their instructions made the border way too long. Squaring up to 3 7/8" did fit.

I have trouble with points anyway, but when one comes out 1/4" different (too long on one side,) that isn't me. (Except for trimming wrong)

All the instructions said was to trim off the ears. I think there was a misprint.

When it calls for 7/8 I always take it up that extra 1/8 to the whole number. 3 7/8 I would cut at 4.