A circular plate rolls in contact with the sides of a rectangular
tray. How much of its circumference comes into contact with the
sides of the tray when it rolls around one circuit?
Tim Rowland introduces irrational numbers
By inscribing a circle in a square and then a square in a circle
find an approximation to pi. By using a hexagon, can you improve on
Read all about the number pi and the mathematicians who have tried to find out its value as accurately as possible.