In an isosceles right triangle, the two legs are equal, and the relationship between the legs and the hypotenuse is given by the Pythagorean theorem:
\[
\text{Hypotenuse}^2 = \text{Leg}^2 + \text{Leg}^2 = 2 \times \text{Leg}^2
\]
Let the length of each leg be \( a = 5\sqrt{2} \) cm.
Step 1: Apply the Pythagorean theorem.
The hypotenuse \( c \) is:
\[
c^2 = 2 \times (5\sqrt{2})^2
\]
Step 2: Simplify the equation.
\[
c^2 = 2 \times 25 \times 2 = 100
\]
\[
c = \sqrt{100} = 10\sqrt{2}
\]
Step 3: Conclusion.
Therefore, the length of the hypotenuse is \( 10\sqrt{2} \) cm.