0) Area of the base square ${\displaystyle A_{0}=1}$
1) Area of the inscribed quarter circle ${\displaystyle A_{1}=0.5}$
2) Area of the additional circle ${\displaystyle A_{2}=({\frac {3}{2}}-{\sqrt {2}})\cdot A_{0}=({\frac {3}{2}}-{\sqrt {2}})\approx 0.086}$

B) Area of black color: ${\displaystyle B=A_{0}-A_{1}-A_{2}=1-0.5-0.086\approx 0.414}$

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