Given that,
Area of circle = \(\frac{1408}7\) cm2
As we know that,
Area of circle = πr2
Now,
πr2 = \(\frac{1408}7\) cm2
\(\Rightarrow \frac{22}7r^2 = \frac{1408}7\) cm2
\(\Rightarrow r^2 = 64\) cm2
\(\Rightarrow r = 8\) cm
\(\therefore d = 8 \times 2 = 16\) cm
Area of square = \(\frac{(\text{diagonal})^2}2\)
\(= \frac{16^2}2\)
\(= \frac{256}2\)
\(= 128\) cm2