\( \triangle ABC \sim \triangle DEF \) and their areas are respectively \(75 \text{ cm}^2\) and \(48 \text{ cm}^2\). If \(EF = 4 \text{ cm}\), then \(BC = \_\_\_\_\_ \text{ cm}\).
Show Hint
In similar triangles, area ratio always equals the square of side ratio. If the area ratio becomes a perfect square fraction like \( \frac{25}{16} \), the corresponding side ratio immediately becomes \( \frac{5}{4} \).