How to find the long side of a right triangle that has two same short side?

To find the hypotenuse of a right triangle, you must use a^2 + b^2 = c^2

* keep in mind the hypotenuse MUST be larger than the legs.

The Pythagorean Theorem comes from making 2 squares from the lengths of each leg (that is why it is a^2 and b^2). The hypotenuse must be equal to the area of the two squares created.

13*12
that would be the maximum you can chose