So I'm making a quilt from the Joy of Quilting Book, and I got all the fabric and started cutting according to the directions. Suddenly, the directions say: follow the directions for conquering half-rectangle units on pp. 162-66, so I go to those pages and it says: place the BiRangle ruler with the diagonal line on the fold. I don't have such a ruler. Can someone tell me what angle that ruler is oriented at, and can I simply cut at that angle and be OK? I need to cut 10 left-angled and 10 right-angled rectangles that will have a final size of 2"x3 1/2". Do you think I should just do the math and figure out how to cut them individually?