Answer:
72 sq cm
Step-by-step explanation:
For any rectangle, the diagonal is the hypotenuse of the right triangle formed by the base of the rectangle(b) and the height (h) of the rectangle
By the Pythogorean formula
[tex]d^{2} = b^{2} + h^{2}[/tex]
where d is the diagonal
For a square, all sides are equal so b = h = a and we get the formula
[tex]d^{2} = a^{2} + a^{2} = 2a^{2}[/tex]
[tex]a^{2} = d^{2} /2[/tex]
In this case we have d =12 so
[tex]a^{2} = 12^{2} /2 = 144/2 = 72[/tex]
But for a square of side a, the area is [tex]a^{2}[/tex] so 72 is the area
