Havplenty

here is a site that helps with the calculation and gives you a visual. i use this method quite a bit. what i have found is that you measure the diagonal of the square size you want (i.e. 5" hst) and add 1/2" for seam allowance to that measurement. then cut the two squares that size. it's the same idea deemail laid out.

http://whipup.net/2011/03/17/guest-b...are-triangles/