Jigsaw

This picture has been going around internet for some time. It is an interesting brain teaser, can you solve it?

Both triangles are made of identical parts. In the bottom one is one empty square though. How is that possible?

Hint

The parts are really identical don’t count them over and over again.

Is everything really what it seems like?

Answer

There is a little trick – what looks like a triangle is not quite triangle in fact.

In the top image the hypotenuse is bowed inside and in the bottom image it’s bowed outside.

If you count the squares and find out how long the legs of red and green triangles are you see that their ratios are not the same which means that their angles are not the same and their hypotenuses in the picture are under a slightly different angle.