2. Let the sides of the rectangular prism be l, b, and h. We know that the total surface area of the prism is 56, so we have:
2(lb+bh+lh)=56
We also know that the sum of all the edges of the prism is 64, so we have:
l+b+h=64
We can solve this system of equations to find that l=8, b=6, and h=4.
The length of the diagonal joining one corner of the prism to the opposite corner is given by:
sqrt(l^2+b^2+h^2)=sqrt(8^2+6^2+4^2)=sqrt(128)=8*sqrt(2)
Therefore, the length of the diagonal is 8*sqrt(2).