Ok. Just one more! this quilt has half square triangles added to the end of 6"x18.5" unfinished rectangle. I don't want to just cut a 6" square and flip it because that wastes so much fabric that I can't afford to waste due to yardage challenges :roll: . What size square do I need to cut so I can cut two triangles from it that will fit my 6x18.5 rectangle?