Answer:
11 meters.
Explanation:
The important thing to note here is that the backyard is a square. Since it's a square, all of its sides all equivalent in length. Thus, let's find the length of the sides. To do this, we use the area formula.
The formula for the area of a square is:

Where n is a side. Since we know the area already, we can find n. Find n:

Since every side in a square are equivalent, all sides are 11 meters in length.
Therefore, each section of the fence should be 11 meters long.