I'm building a square pole barn. I don't own a square. How can I square it?

Question

I've already installed one wall. The length is 12ft. I'm about to install the next wall but I want to be exactly square. So this wall will also be 12ft. So, if A to B = 12ft and B to C = 12ft, what is the length from A to C if it's a perfect square?

Answer 1

To square a building on site, use the 3-4-5 method. Starting with one end of the twelve feet wall, make a triangle by turning clockwise out sixteen feet, and then verify that the starting point is twenty feet from the second point. Continue in the same clockwise until you have four triangles, then subtract four feet from sixteen to get your square footprint.

Answer 2

A to C is the diagonal of a right triangle with sides 12 and 12

AC = sqr(12^2 +12^2) = sqr(288) = 12sqr2 = about 12(1.414) = 16.971 feet

AC is about 17 feet