a & b=a
Explanation:
If a triangles' degrees are 45° 45° and 90°; you have what is called a Special Right Triangle. This is simple and easy to understand with the right equations and setup. Draw yourself a right triangle with side a & b being the same length, label your triangle and angles. I am guessing with the limited question that your side x is either side a or b on your triangle, which means they are both the same length. But if you have a measurement for side c, your hypotenuse, the equation would be: c