Since this is a 45-45-90 triangle, the 2 legs will be the same, meaning that y will also be .
We can then solve for x using the Pythagorean theorem:
Or, we could use a quicker approach: if the triangle is a 45-45-90 triangle, the hypotenuse will be times the length of 1 leg. It essentially does the same thing; it's just faster so you could save time on tests.