\[ C = 2 \pi r \]
\[ C_{синяя} = 2 \times 3.14 \times 12.8 \]
\[ C_{синяя} = 6.28 \times 12.8 \]
\[ C_{синяя} = 80.384 \text{ см} \]
\[ C_{зеленая} = 2 \times 3.14 \times 6.4 \]
\[ C_{зеленая} = 6.28 \times 6.4 \]
\[ C_{зеленая} = 40.192 \text{ см} \]
\[ \Delta C = C_{синяя} - C_{зеленая} \]
\[ \Delta C = 80.384 - 40.192 \]
\[ \Delta C = 40.192 \text{ см} \]
Ответ: 40.192 см