B1. Calculate the area of the shaded figure in the image.

![](https://cdn.mathpix.com/cropped/2024_06_07_c1f0ff7099009a973f5fg-07.jpg?height=251&width=231&top_left_y=363&top_left_x=958)
B1. The shaded part outside the circle in the second square and the shaded part in the first square together cover exactly one square, that is, $\frac{1}{4} a^{2}$. The shaded part in the fourth square covers half of the square, which is $\frac{1}{2} \cdot \frac{1}{4} a^{2}$. Only a quarter of the circle in the second square remains. Since the radius is equal to $\frac{a}{4}$, the area of this part is $\frac{1}{4} \cdot \pi \cdot\left(\frac{a}{4}\right)^{2}$. The area of the shaded figure is therefore $\frac{a^{2}(\pi+24)}{64}$.