Berty100 Posted July 22, 2016 Share Posted July 22, 2016 Couldn't find the maths forum, so let's post it here, and hope there are some smarties around here as well. I looking to convert roof pitch to angle and found a useful site, but can't understand one particular formula. http://www.summerville-home-inspector.com/content/how-convert-roof-pitch-degrees The part I don't understand is in red in the quote below. I understand how to get to .583333 but what I don't get is the exe. To my knowledge exe is the equals button on my calculator, and when I enter the number and press the equals button nothing happens. For example on a 7/12 roof we divide 7 by 12 to get the number .583333. This number is called the tangent. Next we’ll enter inv tan .5833 and exe on our calculator. The result is 30.255012 So how do they reach the number 30.255012? Link to comment Share on other sites More sharing options...
eyecatcher Posted July 22, 2016 Share Posted July 22, 2016 I think you are going to have to ask Mr Pythagorus or Mr Euclid for that answer. the tables relating to Sine, cosine and tangents are like a phone directory and I recall they were quite difficult to negotiate. Then a wonderful invention the scientific calculator appeared in 1980 and you could ask your calculator to work it out. Its not important how the figure 30.255 is arrived at (or maybe it is to you) If you have the length of the horizontal and the height, or even the slope you can use the calculator to get the Angle only. Then as the explanation says, put 30 to one side then multiply the .255 etc x60 to get minutes and then put that number aside and multiply the remainder by 60 again to get the seconds. From my schooling days I used to remember this sentence, it helps when you need to do stuff like this Some Old Horses Can Always Hide Their Old Age (sin opposite/hypotenuse....cosine adlacent/hypotenuse.... tangent opposite/adjacent) By far the easiest way of duplicating existing roof angles as I often do is to simply establish some dimensions and then draw it out to scale. you can then use your set square or a protractor to measure the angle. and yes the EXE button on a calc is the equals, it means Execute calculation....so maybe the inv tang formula already does that on your calculator so just voids it instead? my guess is that you are trying to get the kids homework done before monday!! Link to comment Share on other sites More sharing options...
Berty100 Posted July 22, 2016 Author Share Posted July 22, 2016 Well actually it is important to me how i reach the number 30.255, because that is where I start from, isn't it. So below is my scientific calculator, can you please explain where I enter .5833 and then press which buttons to reach 30.255 ? Link to comment Share on other sites More sharing options...
bankruatsteve Posted July 22, 2016 Share Posted July 22, 2016 Try: enter .58333 then press Inv then Tan. On my scientific calculator it's just Tan-1. Link to comment Share on other sites More sharing options...
Berty100 Posted July 22, 2016 Author Share Posted July 22, 2016 Try: enter .58333 then press Inv then Tan. On my scientific calculator it's just Tan-1. Thanks, that worked. When press Inv the Tan button disappears and is replaced by Tan-1 button. Link to comment Share on other sites More sharing options...
Kwasaki Posted July 22, 2016 Share Posted July 22, 2016 The site has given you the ans 30 degree roof pitch. e,g. 12 m high x 12 horizontal = 45 degree roof pitch. Link to comment Share on other sites More sharing options...
Berty100 Posted July 22, 2016 Author Share Posted July 22, 2016 The site has given you the ans 30 degree roof pitch. e,g. 12 m high x 12 horizontal = 45 degree roof pitch. So you consider it not allowed to calculate it by myself, in case my pitch is different from any of the examples on the site? Link to comment Share on other sites More sharing options...
Kwasaki Posted July 22, 2016 Share Posted July 22, 2016 (edited) The site has given you the ans 30 degree roof pitch. e,g. 12 m high x 12 horizontal = 45 degree roof pitch. So you consider it not allowed to calculate it by myself, in case my pitch is different from any of the examples on the site? Not at all calculate whatever you wish l just don't see the point unless your getting some complicated special factory fabricated flashing items made. Edited July 22, 2016 by Kwasaki Link to comment Share on other sites More sharing options...
Berty100 Posted July 22, 2016 Author Share Posted July 22, 2016 (edited) The site has given you the ans 30 degree roof pitch. e,g. 12 m high x 12 horizontal = 45 degree roof pitch. So you consider it not allowed to calculate it by myself, in case my pitch is different from any of the examples on the site? Not at all calculate whatever you wish l just don't see the point unless your getting some complicated special factory fabricated flashing items made. So you don't see the point of building a roof to the correct specification? A normal Cpac Monier roof should have an angle of at least 28°, otherwise there is a serious risk on water leaks. The tiles I have on my roof are guaranteed by the company against leaks with an angle as low as 17°. Big difference, don't you think, and I don't consider a roof a flashing item either. But a low pitch roof is aesthetic much nicer than a high pitch roof Edited July 22, 2016 by Berty100 Link to comment Share on other sites More sharing options...
Kwasaki Posted July 23, 2016 Share Posted July 23, 2016 (edited) Was only trying help with the calculation you posted and you turn it into an argument, don't know why it's not rocket science. Building a roof to the correct specification on site doesn't need a calculator just tape measure in the right hands. Good-day to you. Edited July 23, 2016 by Kwasaki Link to comment Share on other sites More sharing options...
ubonjoe Posted July 23, 2016 Share Posted July 23, 2016 Topic closed at OP's request. Link to comment Share on other sites More sharing options...
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