If you want the sides vertical like in the diagram, it can be a right triangle; it just has to be perpendicular to the hood, not to the top of the scoop like you have it now.
Thanks ScamperTom - It took a minute to wrap my brain around what you were saying but now I get it.
If I make the triangle 90* perpendicular to the hood, it changes the distance from 3" to 3.1", which I can do easily and accurately.
If 8.5" hood side (base) of the triangle, then the '?' side becomes 9", which is also great.
