To draw a Pythagorean tree, you start with a square. Then you place a right triangle on top of the square so that the hypotenuse of the triangle coincides with the top of the square. Then you place squares on each of the remaining two sides of the triangle so that a side of each square coincides with a side of the triangle. Then repeat the process recursively.

You can control the angle of the original triangle by moving the mouse horizontally. You can control the size of the tree by moving the mouse vertically.