For half square triangles, take the finished size and add 7/8 of an inch and cut a square that size, then cut in half diagonally from corner to corner. This would be for your corner triangles as the bias edges will be attched to the quilt and the outside edges will end up on the straight of grain.
For the smaller ones, you will want to cut those as 1/4 square trianges so the straight of grain is on the outside long edge. Sorry, I cant give you the math on that one.
You could cut a template and add the 1/4 inch seams, then measure it and see what it measures.
Ill see if I can find the math for those.
Someone else will probably be able to give you the answer before I can find it though