Since we know that the area of a square is length x width and that the length=width, we can write an equation in order to find out the side of a square by using what is given. We know that the area of the square is 64 ft^2 which means that each side is equal to 8 using the equation shown below
Now we know all the sides of the square which is 8ft. However, we're not done. The question is asking for the amount of chain fence that is needed in order to enclose the square dog pen. The question is asking us to find the perimeter. Since we know what the sides of this square are, we can either add all the sides or just multiply one of the sides by four. 8 x 4= 32ft Answer: 32ft
