Haha. I only guessed halves being a smart ass. you'll over lay the corners, and what we used to do was, use a garden hose, and hold it on the edge of the beginning and drape it down along the edge and make it form the corner you are looking for inside, and outside edge (use garden hose because it was heavy enough to stay in place but flexible enough to do what you want, and everyone has a hose) once you have the edge shape you want, mark it with pencil and use a grinder with diamond cut off wheel or we used a full size gas powered rock saw, and cut your edge so its nice and curved. GOOD LUCK, and again GREAT PREP work. DONT FORGET TAMP THE SHIT OUT OF IT spraying with hose as you go!