One day, Radius’ parents, Sir Cumference and Lady Di of Ameter, came to watch his lessons. “Show us what you have learned,” they said.
In the riding ring, Radius mounted his horse and Sir D’Grees gave directions. “Knightly right angle, trot!” shouted Sir D’Grees.
Radius rode his horse at a trot to the center of the ring and made an exact right angle turn. It formed a perfect corner.