2 congruent right triangles which form a rectangle.(yellow)
2 rectangles (lightblue, green).
2. Unfortunately you didn't give us the dimension you have obtained by measuring . So I called one side a and estimated the missing length x as .
Then the hypotenuse of the right triangle is
3. Use Pythagorian theorem to calculate the length of y:
4. Calculate the different areas:
The sum of these 3 areas yields the total surface area
5. If and only if you have measured a = 3 cm then the total area is indeed 48 cm².