Question 600797
Perimeter = 4 times one side (since it is a square, all its sides are congruent), then:
P = 4s
Since P = 12: 
12 = 4s
Divide both sides of the equation by 4:
12/4 = s
3 = s
so, each side of the square is 3 cm long
Now.  Area of the square is side times side, or {{{A = s^2}}}
Thus {{{A = 3^2}}}
or {{{A = 9 cm^2}}}