Help

[heirloomcreator]

Let me start off by saying I am new to sewing and quilting and I am very excited and motivated to do a family heirloom quilt. I found a design/project by Quilt dad called rooted/falling leaves, http://www.quiltdad.com/2010/11/falling-leaves.html. This project seems to be a perfect match of the idea I want to complete. It seems easy enough for a beginner, made with squares and half square triangles. I changed the design because I don't want falling leaves to represent my family tree signature quilt, so I made it look like leaves on a tree. Where the leaves are is where i would like to embroider all members of my family, around 40 signatures.
So my question is if I want a finish square of 4 1/2 inches and the unfinished squares are 5 inches, to make my half square triangles a 5 inch square do I have to cut 5 7/8 inch squares?
Thanks