OT, can't remember my geometry, need formula

[Leroy]

I lost the book I had all my geometry formulas in and now I need to find out quick how long the diagonal measurement of a triangle would be. The bottom is 125.0" long with a side of 171.5" and a 90* corner between these measurements. Need to layout foundation marks for backhoe tommorrow

 

[JDB]

A squared + B squared = C squared

I get 212.22"

 

[Anonymous-0]

Yup, JDB's got it right.

 

[Anonymous-0]

I think the formula you need is a squared + b squared = c squared.125 x 125 + 171.5 x 171.5= 45037.25.The square root of the answer is the measurement.I think the answer is 212.21 . This is about the only geometry I remember.

 

[Greg_Ky]

My builders calc. says 211ft. 10 3/16in.

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[Jim.UT]

On a right triangle (90 degree angle on one of the corners) the length of the hypotenuse (long side) is the square root of the sum of the squares of the other two sides. Or square root of (side 1 squared + side 2 squared).

Using your numbers I come up with 212.22" but that's calculating the square root by hand...can't find a calculator that will do square roots right now. You might want to check my math.

 

[Midwest redneck]

Pythagorus and I go way back.
A^2 + B^2 = C^2
Soooooo.......125(125) + 171.5(171.5) = C(C)
Then use the square root key.
I are a college graduate.

 

[Greg_Ky]

The calc. said 212ft. 2 41/64in. Sorry hit the wrong dimension the first time.

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[Anonymous-0]

Square each dimension and total. Get the square root of total. The diagonal should be 212' 1-13/16"

 

[Doug in Illinois]

Didn"t double check any of the math, but thought I would mention I just did an EBAY search for a pocket ref guide I use. It is called pocket ref, by Thomas J Glover. Comes in handy sometimes, and quite a few are listed.

 

[suptscottyb]

New homes aren't the simple boxes they used to be.
So often when laying out a foundation you'll have 4 or 5 boxes you need to square up. A simple way is to use the 3-4-5 formula. A right triangle -(one half of the square)- with one side 3' the other side 4' has a diagonal of 5'. Any muiltiplication of the 3-4-5 works. Use it in inches to hundreds of feet. It makes it quick and easy to line out...btdt.
p.s. you don't have to measure at the corners to be certain you're square enough to dig... leave the exact diagonal math to the formsetters. Besides when you check your diag. lines, it will be the same measurement when square either way - whatever it is. Hope this helps more than not...

 

[suptscottyb]

New homes aren't the simple boxes they used to be.
So often when laying out a foundation you'll have 4 or 5 boxes you need to square up. A simple way is to use the 3-4-5 formula. A right triangle -(one half of the square)- with one side 3' the other side 4' has a diagonal of 5'. Any muiltiplication of the 3-4-5 works. Use it in inches to hundreds of feet. It makes it quick and easy to line out...btdt.
p.s. you don't have to measure at the corners to be certain you're square enough to dig... leave the exact diagonal math to the formsetters. Besides when you check your diag. lines, it will be the same measurement when square either way - whatever it is. Hope this helps more than not...

 

[Anonymous-0]

I agree with this
I get 212 ft and 2 inch and 20.4/32nds
Or 10.2/16th
Or approx 5/8th
So
212' 2 5/8"

 

[Leroy]

Thanks to all that replied. I got the job done. Am building a utility room on the side of a 100+ year old house that only sets on boulders and so to keep the give from freezing and thawing more equal I am around a crawl space building the foundation out of treared posts and treated toung & grove 2 X 6 lumber lined with styofrom insulstion. I am doing the entire job myself with no hired help, I have a rented backhoe to pick up tommorrow morning between 10:00 & 11:00 and return it monday morning. And with this construction no problem with the building permit, permit just askes if it will be more than a hundred feet from a property line, if it is to be a closed addition to the house and approximate size and that is it.