A boat is sent across a river with a velocity of $8\, km/hr$. If the resultant velocity of boat is $10 \,km/hr$, then velocity of the river is ........$km/hr$
A boat is sent across a river with a velocity of $8\, km/hr$. If the resultant velocity of boat is $10 \,km/hr$, then velocity of the river is ........$km/hr$
$10$
$8 $
$6$
$4$
A boat is sent across a river with a velocity of $8\, km/hr$. If the resultant velocity of boat is $10 \,km/hr$, then velocity of the river is ........$km/hr$
Given $\overrightarrow {AB} = $ Velocity of boat $= 8 \,km/hr$
$\overrightarrow {AC} = $ Resultant velocity of boat $= 10 \,km/hr$
$\overrightarrow {BC} = $ Velocity of river $ = \sqrt {A{C^2} - A{B^2}} $
$ = \sqrt {{{(10)}^2} - {{(8)}^2}} = 6\;km/hr$
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