How to get the right measurements for an oval hole?

[Hans-Olof Söderberg]

putting a new metal roof on a barn.
On the roof, there is a vertical round ventilation duct 60 cm in diameter.
The roof slope is 27 degrees.
This must mean that the hole must be oval.
What will the oval measurement of the hole be?
Is there any smart way to calculate this?

 

[O]

Is there any smart way to calculate this?

Answer: YES.
Elementary school math.

 

[Hans-Olof Söderberg]

Oh, then I might have forgotten 🤔
Or maybe I didn't ask the question in a way that's understandable to you?

 

[O]

Well, who knows. It might be included in high school math as well. I've probably forgotten about it too.😄

But it shouldn't be too hard to find if you know where to look. And then there will be a good pedagogical explanation that is probably the easiest to understand. See it as a link to info. That's what I thought. 😇

 

[para]

The oval max measurement will be 673.4 but the hole in the plate will probably be elliptical.
The easiest way is probably to cut another 60-pipe at 27 degrees and use it as a template.
Otherwise, draw it up and print it out.

 

[pjkw]

You have received the answer, but how you calculate it is:
Cos 27 degrees gives 0.89100652
60 divided by 0.89100652 gives 67.339574574605

 

[swirve]

Here is some info, as well as how you can practically create an ellipse shape:
https://math.stackexchange.com/ques...45-roof-how-to-determine-the-roof-holes-shape

 

[plåtrickard]

In reality, the hole doesn't need to be measured to the millimeter, it still requires a cover plate from above.

 

[13th Marine]

Interesting that it's said to be elementary school math, I did a quick search and this way of calculating with sine with friends is (was?) Math D (Math 4 today)? Meaning high school, and probably only those who studied technology/natural sciences and similar disciplines.