Trong công thức cộng vận tốc $\overrightarrow{v13}$ =$\overrightarrow{v12}$ +$\overrightarrow{v23}$ . Biết $\overrightarrow{v12}$ = 30km/h , $\overrightarrow{v23}$=40 km/h . Độ lớn của $\overrightarrow{v13}$ có thể có giá trị nào sau đây? A. 72km/h B. 54km/h C. 9km/h D. 120km/h Giải thích các bước giải hộ mình nhé ^-^

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