Finding the correct angle

[XLMFAB]

Im trying to build a set of ramps for a heavy duty truck to drive on. Im using 4" X 4" X 1/4 square tubing. the length is 12' and the height is 2' 6" with a 4' deck on top for the rear axles. I need to find the formula to achieve the correct angle for the incline. thank you in advance for any help.


4'
███████████
█
█
2' 6" █
█
█
█
████████████████████████████████████████████
12'

[Sonora Iron]

Is this what you’re after?

[UH60LCHIEF]

Delta=17 21'14"
or the arctan of 2.5 / 8
was my guess because it looked like the top was 4'
otherwise it's the arctan of 2.5 / 12 = 11 46'06"

[Sonora Iron]

With 4-foot height.

[FabTech]

I Concur with UH60LCHIEF on the Delta
The hypotenuse for 8’ x 2’-6” would be 8’ - 3 13/16” Delta of 17 21’ 14”
The formula is the Law of Sin

Fab Tech

[Blondie_486]

Is this what you’re after?

You forgot to subtract his 4' deck from the 12' overall length.

[MMW]

Or you could just snap a couple chalk lines on the shop floor & measure it.

[UH60LCHIEF]

I Concur with UH60LCHIEF on the Delta
The hypotenuse for 8’ x 2’-6” would be 8’ - 3 13/16” Delta of 17 21’ 14”
The formula is the Law of Sin

Fab Tech

There's a whole pile of different ways to solve a trig problem. I just used ARCTAN theta (or Tan ^-1) of the ratio of the sides Opposite / adjacent, but law of sines does the trick just the same. You could use Pythagorean theorem to solve the hypotenuse and use any number of other functions as well. There's always like a million ways to skin a cat with a trig problem. Or like MMW said you could just snap a few chalk lines and break out a protractor. My calculator just happened to be sitting right there when I read it. Either way I hope that helps

[Sonora Iron]

You forgot to subtract his 4' deck from the 12' overall length.

I was a little confused on exactly what he was trying to do! And the drawing wasn’t real clear, to me anyway.






http://www.analyzemath.com/Geometry_...alculator.html

[XLMFAB]

Thanks for all the replies. Im trying to save to got to welding school so I can eventually answer my own questions. The ramps have to have a 4' deck for the rear axles. Purpose being that the heavy duty truck is a industrial vacuum truck that has to offload into a 25 yard roll off container.