Question 1155074
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Right angled triangle with one leg of 8 units directed across the river and the other leg of 5 units directed along the rive (current (!)).


The resulting speed is the HYPOTENUSE  {{{sqrt(8^2+5^2)}}} = 9.433 m/s.


<U>ANSWER</U>.  Option A)
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Solved, explained and completed.


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It is about the vector rule of adding velocity vectors.