What is the length of the line segment cut by the square of the parabola y = x

What is the length of the line segment cut by the square of the parabola y = x

Let x = x square, then x = 1, x = 0, so the intersection points are (0,0) and (1,1), so the length of the line segment a of the straight line y = x cut by the square of the parabola y = x is a square = (1-0) square + (1-0) square, a = root 2