angle from pitch

  • Thread starter Thread starter Anderson
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A

Anderson

How can I get the angle from a roof pitch figure(inches of rise to
inches of length)
ie I know a 12-12 roof pitch is 45 degrees.But a 6-12 roof pitch is not
24.5.
This is easy enough to read of a speed square but whats the formula?
 
How can I get the angle from a roof pitch figure(inches of rise to
inches of length)
ie I know a 12-12 roof pitch is 45 degrees.But a 6-12 roof pitch is not
24.5.
This is easy enough to read of a speed square but whats the formula?
Click to expand...

Rise/Run is the tangent of the angle.

So, in degrees in Excel:

=DEGREES(ATAN(rise/run))

6-12 would be about 26.5°


--ron
 
...
...
Rise/Run is the tangent of the angle.

So, in degrees in Excel:

=DEGREES(ATAN(rise/run))
Click to expand...
...

Better to use ATAN2 rather than ATAN (at least that's this respondent's totally
biased opinion having learned this stuff in physics and engineering courses in
which 90 and 270 degree angles had to be accomodated and 0 and 180 degree angles
had to be distinguished).

=DEGREES(ATAN2(run,rise))
 
...
..
..

Better to use ATAN2 rather than ATAN (at least that's this respondent's totally
biased opinion having learned this stuff in physics and engineering courses in
which 90 and 270 degree angles had to be accomodated and 0 and 180 degree angles
had to be distinguished).

=DEGREES(ATAN2(run,rise))
Click to expand...

Cool. I'd not seen that function before.

Although in a roofing situation, I've not seen a roof "run" expressed as other
than a positive number.




--ron
 
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