The area of a regular pentagon looks about twice as a big as the pentangle star drawn within it. Is it?
What is the area of the quadrilateral APOQ? Working on the building blocks will give you some insights that may help you to work it out.
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?
How could you organise the cards? Are there any pieces of information you haven't used yet? Are there any cards with useless information? Could you combine the information on several cards to generate new pieces of information?