Answer:
5 in x 5 in
Explanation:
The area of the rectangle is given by:

Where x and y are the length and width of the rectangle.
The perimeter is:

The value of x for which the derivate of the perimeter function is zero is the length that yields the smallest perimeter:

The value of y is:

Therefore, the dimensions that yield the smallest perimeter are 5 in x 5 in.