Here's something I'm ponying up to try to make a half pyramid tent without seams on the roof edges.
I'm making some assumptions here that the back width of the tent will be twice the width of the fabric itself. This thing is not to scale though. The pentagram is automatically being dimensioned by my graphics program. I couldn't tailor it like I wanted.
I tried trig, but I kept coming up with two unknown variables. Through some geometry inspection, it seems that the angle between the door line and the foot of the side wall needs to be 90 degrees.
I've been trying to find a formula that I could use to exactly place points for cutting, and my trig is too ancient to get far right now.
I know I could lay this thing out with a large compass, which is likely what I'll do. I was just trying to calculate the x and the y of that 90 degree point (B) to do it in a Cartesian way so it would be easier to make a pattern that others could use.
If someone had a formula that someone could just plug in fabric width, apex height, and tent width, that would be wonnamous.
This thing is not proportioned right. I just eyeballed it to get the angle to approximately 90 degrees, and wasn't totally successful. This is a depiction of the fabric flattened, not of a floor plan.
Though my geometry verified it should be 90 degrees, logically it seems like it should be 90 degrees also, because when you're looking from the side of the erected tent, and the front of the tent is making a 90 degree angle with the ground, and the sidewall are squared to the whole floor plan, the front of the tent should make a 90 degree angle with the side wall floor line.