King Arthur has issued a challenge. The first knight to find the sword Edgecalibur will be the next king. Join Sir Cumference, Lady Di of Ameter, and their son, Radius, as they race to help their friend, Vertex, find the sword and discover the secrets of cubes, pyramids, cylinders, and cones. A funny and pun-filled retelling of "The Sword and Stone" that introduces readers to mathematical angles. King Arthur has hidden his sword, Edgecalibur and issued a challenge to the knights. The first knight to find the sword will be the next king. Can Sir Cumference and Lady Di point Radius's best friend, Vertex in the right direction? Will Vertex's sharp thinking give him the edge? Join Sir Cumference, Lady Di of Ameter, and their son, Radius, in this new adventure where they race to help Vertex find the sword and discover the secrets of cubes, pyramids, cylinders, and cones.