Answer:
It will be 10.
Explanation:
This is a common 90 45 45 triangle. The sides can easily be found by remembering that if the two similar sides are x, the third side will be x square root 2. Since x is 5sqrt2, and we are multiplying it by another sqrt2, it would be 5sqrt4, it can be simplified to equal 10, since sqrt4 is just 2.