Area CEB is equal to area of the square OAEF minus area of the quarter circle OABCF minus four times the area of CED.

$A_{CED} = 8.68 \, \text{ cm}^2$ → *See how it was found*

Area of CEB

$A_{CEB} = A_{square} - A_{OABCF} - 4A_{CED}$

$A_{CEB} = 20^2 - \frac{1}{4} \pi (20^2) - 4(8.68)$

$A_{CEB} = 51.12 \, \text{ cm}^2$

Required Area

$A_{required} = 4A_{CEB} = 4(51.12)$

$A_{required} = 204.48 \, \text{ cm}^2$ *answer*