Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: the area of a circular field is 13.86 hectares . find the cost of fencing it at the rate of rs . 4.90 per metre .
6468
5122.51 m²