Kristen needs to enclose a rectangular pen for her cows. Kristen only has 400 feet of fencing material so she will use the side of a barn as one side of the fence. With this amount of fencing material, the largest possible area that she can get for the pen is square feet.

The largest possible area is 10,000 square feet

Step-by-step explanation:

Since she has 400 ft of fencing material, this means that the perimeter of the pen will be 400 ft

Mathematically, the perimeter of a rectangle is is;

2(l + b) = 400

Thus, l + b = 400/2

l + b =200

This means the length and width pen add up to 200

Mathematically, the maximum area can be obtained if the side of the length and the width are equal

So we will have to share the 200 into 2 , that makes 100 for each

The largest possible area is thus;

100 ft * 100 ft = 10,000 square feet