You will make all other calculations for each set of two (2)Mary's Triangles units based on this measurement. For the examples, we use a 4" finished (41/2" raw) Mary's Triangle unit. In the examples, width = the short side measure; length = the long side measure.
For each TWO Mary's Triangle units:
Example: 21/2"
Example: Width = 21/2" + 1" = 31/2"
Width = Measurement from step 1 multiplied by 2 minus 1/2inch seam allowance. Example: 21/2" X 2  1/2" = 41/2" Length = Width computed above for this large rectangle plus 1" Example: 41/2" + 1" = 51/2" Therefore, cut one rectangle at 41/2" X 51/2". 
