We are doing a project with Pythagorean Theorem where we need to measure a wall and then make pennants that fit on the string. I did that, my wall is 50in, my pennants were cut from a 9 by 9 square. When I measured the diagonal, it was 12.5, but when I used the Pythagorean Theorem it was 12.8. I am supposed to explain why they are different, but I don't know why they would be, especially since measuring it didn't come out right. 4 of them should have fit perfectly, and they were too long. Why didn't the measurement and the Pythagorean Theorem work out differently?

Question

We are doing a project with Pythagorean Theorem where we need to measure a wall and then make pennants that fit on the string.  I did that, my wall is 50in, my pennants were cut from a 9 by 9 square.  When I measured the diagonal, it was 12.5, but when I used the Pythagorean Theorem it was 12.8.  I am supposed to explain why they are different, but I don't know why they would be, especially since measuring it didn't come out right.  4 of them should have fit perfectly, and they were too long.  Why didn't the measurement and the Pythagorean Theorem work out differently?

Reiny · Accepted Answer

9^2 + 9^2
= 81+81 = 162
√162 = 12.7279... = appr 12.8

Don't expect your "measurement" to match the accurate mathematical answer.
I could be your drawing, it could be your ruler, it could be your estimation.
Since the old imperial system of measurement using inches is not very
suitable for decimals, this could be another problem.