Originally Posted by justwannaquilt
If my math is correct (its still eary so it might be wrong) this is IMPOSSIBLE! To make 5 1/2 inch UNFINISHED half square triangle you would of had to START with a at LEAST a block that measured 6 3/8 (6 1/2 if your gonna square it up) Since you started with a 6 inch block you can only square this block up to 5 inches.
The formula for HST's is to add 7/8" to the
FINISHED size (if you're using the exact method).
That breaks down to 1/2" for the seam allowance and 3/8" for the angle.
So if the goal was a 5" FINISHED HST (which I think it was), starting with 6" squares leaves just a tiny bit of extra fabric to trim down the HST to 5.5" UNFINISHED.