[
Possibly silly question -- when connecting a triangle to a rectangle do you match them on he edge or do you center them? I think I just figured out centering them was important. "
These triangles are called " setting" triangles and can be used on the corners or on the side to square up design when putting blocks "on-point" It is called "0n-point " when you take a square block and turn it so it is a diamond.
check the following link or the web for how to determine the size of the setting triangle. it a little more complicated to figure the size out than just adding 7/8" to block size. . Here is Bonnie hunter's version:
http://www.stcroixquilters.com/setting%20triangles.htm. All the calculation has to do with geomerty and who cares why.
Alo you want to match the centers of the block and the triangle and let te edge extend past edge of block a little. Better to be sightly longer on the edge than too short. Do not match the edges and becareful not to stretch the diaginol of the triangle.