In a 45°-90°90° triangle, the length of the hypotenuse is 2–sqrt2 times each leg.

If x is the leg length, then we can write:

\(25=\sqrt{2\times x}\)

\(\frac{25}{\sqrt 2}= x\)

\(\frac{25}{\sqrt 2}\times \frac{\sqrt 2}{\sqrt 2}\)

\(x=\frac{(25\times \sqrt2)}{2}\)

If x is the leg length, then we can write:

\(25=\sqrt{2\times x}\)

\(\frac{25}{\sqrt 2}= x\)

\(\frac{25}{\sqrt 2}\times \frac{\sqrt 2}{\sqrt 2}\)

\(x=\frac{(25\times \sqrt2)}{2}\)