Hey Guys, For a maths assignment, we were given this question to complete: http://nrich.maths.org/5673 I'm having an discussion with a friend of how best to approach it. Should I work out and differentiate the area or perimeter (for the circle)? If we're finding the cost of materials, then circumference would be more appropriate than the area. Or should we look at both? Sigh, isn't it always the most basic part of a problem that stumps us? Thanks for your assistance.