Q: Compare the area of domains A and B? 
The logo opposite is constituted by two semicircles and by a quarter
  circle. Compare the area of domains A and B


I tried to compare the area of one of the semicircles to the area of a quarter of circles, to be able to express this relation according to areas A, B and C but with no luck


*

*Is there any way to solve that problem ?


A: Hint
If the diameter of semicircles is $d$, and C, A, B are the areas of the regions indicated by these letters, we have:
$
2C+A+B=\frac{\pi}{4}d^2
$
because this is the area of a quarter of a circle of radius $r=d$
$
C+A=\frac{\pi}{8}d^2
$
because this is the area of a semicircle of radius $\frac{1}{2}d$
so
$$
2C+2A=2C+A+B
$$
