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?
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 the approximation?
Tim Rowland introduces irrational numbers
Read all about the number pi and the mathematicians who have tried to find out its value as accurately as possible.