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# A man travels 1 km east , then 5 km due south , then 2 km due east and finally 9 km due north. How far is he from the starting point ?

$\begin{array}{1 1}(A)\;3\;km \\(B)\;5\;km \\(C)\;4\;km\\(D)\;6\;km \end{array}$

$\overrightarrow {S}= \overrightarrow{S_1}+\overrightarrow{S_2}+\overrightarrow{S_3}+\overrightarrow{S_4}$
$\qquad=(i) +(-5j) +(2i) +(9j)$
$\qquad= 3i+4j$
$| \overrightarrow {S}|=\sqrt {(3)^2 +(4)^2}= 5 km$
Hence B is the correct answer.