1. The diagonals of a rectangle are always equal. So AD = BC.
2. The radius of a circle is always the same. So CB = CE.
Mama mia! If CE = 20, then AD = 20!
The drawing known as The Vitruvian Man was done by Leonardo DaVinci, (1452-1519), a real Wizard. He used simple geometry to understand and describe the nature of Man, not only in his engineering and his studies of anatomy, but also in his art.
