A Pythagoras tree is a fractal, first discovered by the Dutch electrical design engineer and mathematics teacher Albert E. Bosman. In 1942, he was a forced laborer in Nazi Germany, where he was ordered to design parts for submarines. He sabotaged by stalling, but making it look like he was busy working on tasks that were forced upon him. Instead, he secretly drew smaller and smaller right-angled triangles with squares sharing sides with the triangles. After many triangles and squares, his drawing revealed a remarkable figure.
This fractal later became known as the "Pythagoras tree", as the areas of the squares relate to each other according to the Pythagorean theorem. Bosman drew his tree with angle α = 45°, which results in a bilaterally symmetrical tree, i.e. having a left and a right side that are mirror images of each other. But, of course, the angles can be anything between 0 and 90 degrees.