This question was uploaded on 11/01/22 on social media accounts.
Solution:
Blue Area = A(⌔ABD) - A(⌔OBC) - A(ΔAOC)
\[\Rightarrow Area=\pi(12)^2\left(\frac{30}{360}\right)-\pi(6)^2\left(\frac{60}{360}\right)-\frac12(6)(6)\sin(120)\]
\[\Rightarrow Area=12\pi-6\pi-9\sqrt3=6\pi-9\sqrt3\]
