Firstly, just to give context, I'm starting an OU degree in Autumn with Math as my first module. My math is questionable so I've been given a few practise papers to prepare myself and there are a few questions I just can't grasp, even with all the materials I've been given.
The Question:
Consider the following exam question and a student’s attempt at a solution.
''Anny wants to fence off an area in the middle of a field in order to
make an enclosure for some pigs. She has 200 metres of fencing
available. Should she make the fencing in the shape of a square or a
circle, in order to enclose the greatest area?''
Annie's solution:
200 = 2πr
= πr^2 = 3183.
200 = 4l
l^2 = 2500, so circle.
(a) Criticise the solution, explaining why it is difficult to follow.
(b) Write out a better solution.
Thanks

Jay
EDIT: Sorry if this is the wrong place to post! Like I said, my math is questionable so I'm even unsure about the topic title!