All 4 sides of a square must be equal to each other, and the area of a square can be found by multiplying one side by another side [or squaring one side: (side^2)]. Therefore, you can set up the equation as side^2 = 121cm and take the square root of each side, which will give you side = 11cm. Every side is 11cm, including the base. *Answer: 11cm*