MiketheEngineer wrote,
"I do these in my sleep trying to got to sleep."
Nice Mike. I don't have time to do trig while I'm sleeping, too busy writing spreadsheets. I should give it a try tho. Seems like it'd be a lot easier. I might get some rest!
Basically you take the tangent of both sides knowing that this does not change the quality. tan of arctan cancels out and then you multiply both sides by 12 and voila!
Thanks for the replies. I needed this formula for a spreadsheet. I used it, among others, to find the pitch of a valley rafter. In this case the two roofs that form the valley do not have like pitches. It works fine.