Carol: I have only three suggestions. First measure your half square triangle to make sure that it measures exactly what Bonnie suggested. Then use the rulers she suggested to make the triangles, blunting the corners so you know just where to join them. Then use the same rulers to true up the finished product. If your not cutting off any from the long edge you won't lose your points. The main thing I learned is if you err, err on the side of putting more towards the top. When I started mine measured exactly what yours measures. Please don't get discouraged. I found "perfecting" one before going on to the others really helped. The up side is that I really learned a lot about joining unequal triangles. Hope this makes sense. Let us know how you are doing.