Answer:
\(15cm^2\)
Explanation:
\(64-\frac{1}{2} \times 4 \times 8-\frac{1}{2} \times 4 \times 7-\frac{1}{2} \times 1 \times 8-\frac{1}{2} \times 2 \sqrt{5} x=\frac{1}{2} \times 2 \sqrt{5} x\)
\(x=3 \sqrt{5}\)
Blue Area \(=\frac{1}{2} \times 2 \sqrt{5} \times 3 \sqrt{5}=15\)
source: Twitter