Answers (2)
It depends on the sides.
An acre is 43,560 square feet. It is defined as ten square chains. That is Gunter's chain, en.wikipedia.org/wiki/Gunter%27s_chain The chain is 66 feet long, so a square chain is 4356 square feet, and an acre is ten times that.
2.13 acres = 92782.8 square feet
Assuming an equilateral triangle, area = s^2 (√3)/4
en.wikipedia.org/wiki/Equilateral_triangle
92782.8 = 0.433 s^2
s^2 = 92782.8/0.433 = 214278.9838
s = 462.9 feet
perimeter = 3s = 1388.7 feet <-- ANSWER
If the triangle is not equilateral then you would need to find the base and height.
I tried to run your acreage on the calculator but the amount of fencing changes depending on what type of fencing you want to use. So you need to enter the acreage in the box on the right then choose your fencing type and submit.
https://
sasteelco.com/fencing-center/fence-calculator/
To click on the link remove the space after the //