3420.22 – The Area of a Cross

In triangle ABC, we have

$$\begin{align*}w^2 + (2w)^2 &= 10^2 \\5w^2 &= 100 \\w^2 &= 20\end{align*}$$

Thus each small square has area $20$, and the total area is $100$.

That's it for the problem, but since $100 = 10^2$ don't you wonder whether the cross can be cut into pieces and re-arranged as a $10 \times 10$ square?