It appears as if 12cm is half the length of the side so we can assume that the total length of one side is 24cm.
The area of a square is given by the equation [tex]A=s^{2}[/tex] where s is the length of the side.
[tex]A=24^{2}[/tex]
A=576
The area of this square is 576cm2.
Hope this helps!
