Hello, fwl200!

The perimeter of an isosceles right triangle is: .

What is the length of the hypotenuse?

I understand that it should be: .

but not sure how to solve it.

The equal sides are ; the hypotenuse is

We have: .

Factor: .

Hence: .

Rationalize: .

. . . . . .

Therefore, the hypotenuse is: .