New quilt being developed

It never ceases to amaze me how much time passes in between my posts - usually double what I think it is. Another two weeks have passed, and admittedly I've been sick with a bad cold that I still have two weeks on, but boy! does time fly!
Today's photo shows the process of understanding the construction of the quilt I want to make and calculating my fabric requirements. I do not have any 'actual' measurements of the tessellated tile floor I wish to replicate so have begun with a 12" central block. I then got into a bit of difficulty working out how big it would become when I only knew the measurement of the hypotenuse and had to pull out some high school maths skills to figure it out. Even now, I'm not sure I have a handle on it. My theory is, that if I post here regularly with updates on this quilt, I shall actually get it done, because I'll feel accountable. So here goes ...