Math CentralQuandaries & Queries


Question from bill:

I am a contractor & i am laying out some piers in an L shape i need to know how to tell if they are square one side of my L is 18 feet the other is 11 feet 6 inches what is the formula to find out what the distance from point to point should be for square . I appreciate any help u can give me thank you

Hi Bill,

The converse of the Pythagorean theorem says that if you have a triangle with side lengths a, b and c units and a2 + b2 = c2 then there is a right angle between the sides with lengths a and b. You have sides of length 18 feet and 11.5 feet and

182 + 11.52 = 456.25 = 21.362.

Thus you need a distance of 21.36 feet which is 21 feet 4 5/16 inches.


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