area and perimeter

[BMAD]

Carter fenced in a rectangular plot of land and then divided it into two halves by putting another fence along the main diagonal. This diagonal fence measured 41 metres exactly.

Martindale also fenced in a rectangular plot of land in a similar way (including the diagonal fence) but his rectangle was one-third greater in area than Carter's plot and used less fencing.

In both plots all the the dimensions (lengths, widths and diagonals) were a whole number of metres.

How much more fencing did Carter use than Martindale?

[bonanova]

13 meters[spoiler=because]Carter: 41² = 40² + 9². Area: 360 Fence: 139
Martindale: Area = 480
Integer lengths 24 30 32 40 48 produce integer widths 20 16 15 12 10.
Of these, 30, 16 produce integer diagonal 34. Fence: 126.