How to Find Stringer Length Using Pythagorean Theorem

Oh in this section I want to show you how to figure the length of experiment and your stairways looked something like this the platform would be here and the floor would be here and then these are what you walk on these are called treads and these are risers so over here this is our stringer here's our tray here's our regular and then this is our platform and we get this made you might by just taking a tape measure in measuring from our floor to the top of the platform and so this area here is called our total rise and when we mentioned that we had 89 inches then there's some things you have to know you have to know that the ideal riser height this height here is 7 inches the ideal tread is somewhere between 10 and 11 inches or the combination be like 17 or 18 inches so we have to do we could get by if we just had long enough legs we can step from here to here but unfortunately some of us are short and so what we have to do we have to figure out how many risers we need and so I take my total ride which is 89 inches and I divide that by the ideal writer which is 7 inches and when I come up with that my ideal my number would be 12 point 7 and something I really don't care about this number this is the number I care about because that's how I make rice which I have and then you'll always have one less tread than writer because my top tread is here ok so now we know is that we have 12 risers we have one less treads we have 11 trigger and if each of our treads are 10 inches then I can figure out the distance from here to the bottom of my stringer or me from from this point to this point where this lands and so I take my memories one of these we said was around chances and if I had 11 of them if I take that 11 times by 10 that my total run is a hundred and ten inches okay and then so if we if you remember the dadgum theorem it's a squared plus B squared equals remember was our total rice which is 89 inches our B squared would be our total run which is a hundred changes so if I take my 89 times 89 it would come out the seven nine to one so I get 7 to 9 to 1 and B squared would be 110 times 1/10 which is 1 to 1 0 0 when I add my 79 point to 1 and a 1 to 1 0 0 I come out with 2 0 0 to 1 and then I take the square root of that to get this way here remember this is C squared so when I get the square root of that it comes out to 1 for 1 point 4 9 5 5 8 inches and then if we remember how to convert inches to Feet in inches when we take this one for one point four nine five five eight divided by 12 I come up with 11 feet point seven nine one I ate again I'm gonna take off the 11th which leaves me the point seven nine one two nine eight this is interest so I'm going to - that out I have 12 inches in a foot I multiply that times 12 and I get nine point four nine five inches so right now I got eleven feet nine inches and then I'm gonna - a nine which gives me my point four nine five sixteen I read it in 16 so times 16 equals 8 16 or 1/2 inch so my length here would be 11 foot 9 and 1/2 inches and since our strikers come in multiples of 2 the stringer them of beer we know our our total run we know the lengths of stringer we have we also know how many risers and how many treads but we don't know is the exact height to be tracer we know that the ideal riser is around 7 inches so I'm gonna take that 89 inches divided by 7 and I know I got 12 of them so now I'm going to take this my rice didn't change so I'm going to take that 89 and I'm going to divide now by the number of risers I have so when I divide this 89 by 12 gives me seven point four one six six six we know how many risers we have we know that the ideal rise is seven inches so if I take my 12 dividing it here I get seven point four one six six seven inches and then this is my fraction smallest fraction on my tape is 16 so I'm going to take this seven point four one six six minus a 7 gives me a point four one six six multiply it times 16 and I get six point six six five six since this number is larger than five I'm going to raise it to a seven and it'd be seven sixteenths so each of my risers n would be seven and seven six beats

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Length: 7min 8sec (428 seconds)

Published: Fri Feb 13 2015