Start by drawing a square with dimensions of 1 x 1. Then, draw a line from the top right hand corner to the base of the square such that the line you're drawing intersects 1/3 of the distance from the bottom left hand corner. Repeat this for the bottom left hand corner so that a line from this corner intersects the top line of the square 1/3 of the distance from the top right hand corner. Lable these two triangles as triangle 1 and triangle 2. Wish I could include a picture, but can't seem to.

The area of triangle 1 and 2 is the equation A = 1/2

2bh. Since the square is 1m X 1m, we know the area of triangle 1 and 2 must each be 1/3 of the total. So, ⅓ = ⅟2bh. We also know h = 1. Therefore, ⅓ = ⅟2b(1). Solving for b, we find b = 2/3. Then we can use the Pythagorean Theorem a^2 + b^2 = c^2. We know a and b, therefore we can solve for c. Let a = 1, b = 2/3. We find c = √(13/9), or c = (√13)/3. In this case c, or what you are calling x, is (√13)/3.

This creates two triangles with a hypotenuse of equal lengths, and 3 shapes with equal area. This is the best I can offer based on the info you provided. Hope it helps.