Below is the graph of a trigonometric function. It intersects its midline at $\left(\frac{3}{5} \pi, 8\right)$ and again at $\left(\frac{7}{5} \pi, 8\right)$. What is the period of the function? Give an exact value.

Please directly answer the question and provide the final value, e.g., 1, 2.5, 300.
Question: Below is the graph of a trigonometric function. It intersects its midline at $\left(\frac{3}{5} \pi, 8\right)$ and again at $\left(\frac{7}{5} \pi, 8\right)$. What is the period of the function? Give an exact value.

Please first conduct reasoning, and then answer the question and provide the final value, e.g., 1, 2.5, 300, at the end.
Question: Below is the graph of a trigonometric function. It intersects its midline at $\left(\frac{3}{5} \pi, 8\right)$ and again at $\left(\frac{7}{5} \pi, 8\right)$. What is the period of the function? Give an exact value.
