Riddle Me This? What is the answer to this riddle?

[EVIE EVIE EVIE]

A Geographer, A physicist, and a mathematician are asked by a farmer to cover the greatest area of land using the least amount of fence. The Geographer thought that putting a fence in a straight line fencing off half the earth was the answer. The physicist fenced a large triangle and claimed it was the answer. The mathematician just laughed and he had the right answer what was it?
din ding ding ding jason has the answer! THE ANSWER AS HE SAID IS: HE made a small fence around himself and said he was on the outside so basically everything was fenced in.

 

[Ray]

Jason's got it. Good one xD

 

[Jason]

He made a small fence in a circle and said that the smaller area that would normally be assumed to be the inside was actually the outside of the fence, meaning pretty much the whole planet was fenced in.

 

[Luis]

use no fencing at all?

 

[fryinbrian]

The farmer doesn't need any fence for the biggest area.
Just the whole world.

 

[Treboria]

yup i'm assuming you don't need any fence if your including water.