Looking at the block, each of the squares would need to be 1.5" finished to make a 9" block, which means that the squares would be cut at 2". The 1/2 square triangles would be cut at 1.5" + 7/8" or 2 3/8" and cut on the diagonal. I usually cut the 1/2 square triangle pieces larger (2.75) and trim after pieceing. I use the draw a diagonal line and sew on either side, cut apart and press then trim to proper size (2").