Question 8
There are one semicircle and three shaded circles, $C_1,C_2,C_3$, where the radii of the two smaller shaded circles, $C_2$ and $C_3$, are equal. Each of $C_1,C_2,C_3$ is tangent to the semicircle and $C_1$ is tangent to each of $C_2,C_3$. Each shaded circle is also tangent to the diameter of the semicircle, with $C_1$ tangent to that diameter at the centre of the semicircle, as shown. If the total shaded area is $777\text{ cm}^2$, what is the unshaded area, in $\text{cm}^2$? (Take $\pi=\frac{22}{7}$.)
