# Refraction of a water wave

The above is the wave form of a water wave which was generated at the left side of the pool and has a constant frequency. The boundary surface between the deep and shallow areas forms a $$45°$$ angle with the wave front in the deep area, and a $$30°$$ angle with the wave front in the shallow area, as shown above. Let $$f_d$$ and $$v_d$$ be the frequency and speed of the water wave in the deep area, respectively. Similarly, let $$f_s$$ and $$v_s$$ be the frequency and speed of the water wave in the shallow area, respectively. What are the ratios $$f_d:f_s$$ and $$v_d:v_s?$$

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