I've had two or three folks having trouble with making their trees at 45 degree angles. There were comments on the Moda site and on my own blog post about it. This is SUPER important since the shape of the entire quilt depends on this. I am SO SORRY that folks are having trouble with this. I was intentionally a little vague in the original post because I knew that every cutting mat will be a little different and I thought I would save confusion by letting you figure it out on your own mat for yourself. CLEARLY, that was the wrong decision on my part. :) Please forgive me for the trouble this may have caused you. Hopefully this post will clear things up considerably.
Unfortunately, I no longer have the original quilt. My mother has it. 2000 miles away from here. So pretend that this crazy rainbow fabric looks like a Christmas tree. If you have toddlers like I do, it's not so hard to imagine after all. ;-)
Your 5 strips (2 1/2" wide) sewn together should measure 10 1/2" top to bottom now. For demonstration purposes, I cut myself a 10 1/2" wide strip of fabric.
Below is a picture of my cutting mat. The first time I made a tree skirt like this, my trees were not 10 1/2" tall; instead they were 12" tall. So the black ink you see on my cutting mat was originally for a 12" tree.
Do you see this right angle here below? That's 90 degrees.
A closer look for you:
Half of 90 is 45, so this