I think it would make a difference. There are 360 degrees in a circle so if you are making any circle or half circle or any part of a circle shapes, your 10 degree one would make it a different size. You could maybe try and "fudge" by using a larger seam, but by how much is beyond me. You could try using the one of the shorter 9-degree ones and maybe extending the length with a straight edge and make a cardboard or plastic template to use instead