Fabricating hood scoop and bad at math... any help?

I wonder if any of you can help me with some design/math problems. My high school math ran out right at A2 + B2 = C2 (which has totally come in handy) but there might possibly know some formulas that could help!

Here’s the situation: I’m trying to fabricate a hood scoop for the beater race car (73 Dart Sport)

• 24” wide – this part is easy
• 25.5” long from front of scoop to cowl – this is where it gets complicated
• And… have the top in two parts:
  • First part is “flat” on top and 15.96871” long (hooray for A2 + B2 = C2 !!)
  • Second part (angling down tow cowl) is I don’t know how many inches long.
• Furthermore… as the air filter is level with the engine but the hood slopes downward, the scoop needs to be higher in front than in the back.
• So… the front of the ‘flat’ part of the hood scoop needs to be 4” high off the hood and the back 3” high. I have mocked this up with cardboard and can easily cut out vertical side strips that are 4” tall at one end and 3” at the other
• Thus the sloping back part will be supported by vertical triangles…
  • BUT it is clear to me that I cannot use a right angle triangle as it changes the angle. I tried this and it looked wrong.
  • I don’t know how to do the math for non-right triangles!
• Finally, I need to add an inch to both sides and the back to bend at a 90* angle to bolt/rivet to the hood.

Attached are various pictures/schematics. Is there something obvious I’m missing? Is there a formula I can use to figure out how long to make the "slanty" part" (back 3rd)?

The eventual goal is to have hard numbers for all dimensions and try to cut this out of a piece of flat sheet metal (so 2-dimensional), then bend the metal with a sheet metal brake in the right places, and then weld the seams.

Any magic formulas you might know?