The square's diagonal is the triangle's hypotenuse.
The Pythagorean theorem is = [tex]a^{2}+b^{2}=c^{2}[/tex]
Here, 'c' is the hypotenuse and 'a' and 'b' are the two sides of the triangle.
As the side is given 12 inches, so this becomes
[tex]12^{2}+12^{2}=d^{2}[/tex]
[tex]144+144=d^{2}[/tex]
[tex]d^{2}=288[/tex]
[tex]d=\sqrt{288}[/tex]
[tex]d=16.97[/tex] inches
