That's actually pretty clever.
This isn't the solution, it wouldn't matter if the hypotenuse is straight or not...
The paradox of a triangle.
Not so much a paradox as slight of hand. I've actually seen this done two ways. One was a bent hypotenuse like the one shown here, and the other was curved. The curved one was much harder to spot.
LOL @ w4nn4b3. Did you happen to fail high school math?
A better explanation than I've seen elsewhere. Still, I've never liked this puzzle because it talks about "area of a triangle," which is intentionally misleading. Neither of the figures are a triangle.
it's not a paradox, but a swindle
I've seen this before and noticed the slight bend in the hypotenuse, but had never actually seen the solution before.