I'm only writing this all out because you say you're a novice.
Are you trying to make a HST (Half Square Triangle) block? Which is a square made up of 2 triangles, split diagonally between 2 fabrics?
Or QST (Quarter Square Triangles).
Do you want the "finished block" to be 2 inches?
Can you post a picture of the pattern? You'd get more direct answers that way.
And if you're going to be dealing with smaller sizes like you listed, it would be helpful to get a smaller ruler, maybe a 6" square, or something around that size.
It is very cumbersome to be dealing with so "extra" ruler. Your ruler collection will most certainly grow in the future. ;-)