Perpendicular in Right-Angled Triangle makes two Similar Triangles/Porism

Porism to Perpendicular in Right-Angled Triangle makes two Similar Triangles

 * From this it is clear that, if in a right-angled triangle a perpendicular be drawn from the right angle to the base, the straight line so drawn is a mean proportional between the segments of the base.

Proof
Follows directly from Perpendicular in Right-Angled Triangle makes two Similar Triangles.