Notes
squares and a semi-circle solution

Solution to the Squares and a Semi-Circle Puzzle

Solution by Circumference of a Circle

The diameter of the circle is $2$, so the circumference of the semi-circle is $\frac{1}{2} \pi \times 2 = \pi$. There are seven squares along the bottom, so each individual square has side length $\frac{2}{7}$ and the perimeter of the lower region is $(2 + 7 + 2) \times \frac{2}{7} = \frac{22}{7}$.

This is one of the classic approximations for pi. The total perimeter of the combined shape is therefore: