I've been pretty much making up this design as I go along, no pattern so no directions to follow. That means I need to figure out the size of all the pieces myself. That means knowing the formula for calculating the size of side triangles! That means a visit to my handy reference book, The Quilters Ultimate Visual Guide.
This book appears to be out of print, which is unfortunate because I use it all the time. (Amazon.com has used copies available through third parties.) Though many quilting reference needs can be met by information on the web these days, it is so handy to have them on the shelf in my sewing room.
Everything I need to know about setting triangles is right there on page 227. There is the formula for calculating the size of the square needed to cut both side and corner triangles, as well as handy reference chart. In case you need it, the formula for side triangles is:
(finished size of block in inches x 1.414) +1.25" = size to cut square
The square is then cut on each diagonal, to yield four setting triangles. For example, if the finished size of your block is 10", the formula is:
10" x 1.414 = 14.14" + 1.25" = 15.39" or 15.5"
Time to go cut some more blocks. I should have more progress on this quilt to share next week.