Originally Posted by sushi
PaperPrincess is correct in reducing the starting lengths of sides A and B of the triangle by 1/2" to 4 3/8". (I was wrong in reducing them by only 1/4".) Her calculation of 6.18" (~6") looks right to me as the finished size of the block. (While I enjoyed reading it, I don't agree with the next step she took, however, which reduced the block to 5".)
Actually there's only 1/4" from each triangle, because there's only one seam on one leg of the triangle, so you were right that it's 4 5/8" and about 6.5" finished.