Many people seem to struggle with having fabric cut large enough to cover the space. I don't cut individual pieces, I cut a strip. For example to cut for piece #2:you need to measure across the shape perpendicular to the seam line between piece # 1 & # 2. Go across all the way to the widest area of the opposite seam line and then add 1/4" seam allowance on both ends. I usually add an additional 1/8" to this for my cut amount. After sewing each piece on, press and then cut off the strip from your sewn block. Yes, with this method you will have a bit more to cut off, but it's worth it to me to not worry my fabric won't be large enough to cover the space. If using a pattern with lots of triangles, it's much easier to use this method than trying to cut fabric to fit that flipped over odd shape.