Answer: 11.8 km
Step-by-step explanation:
The resulting figure is a right angled triangle shown below
[tex]$Apply the Pythagorean theorem to find out the magnitude of the resultant vector $A B$ in the triangle $A B C$ as follows -$\begin{aligned}&A B^{2}=B C^{2}+C A^{2} \text { (Hypotenuse }{ }^{2}=\text { Base }^{2}+\text { Adjacent }^{2} \text { ) } \\&=7.4^{2}+9.2^{2} \\&=139.4 \\&A B=11.806777 \\&\quad A B \approx 11.8 \mathrm{~km} \text { (Rounded off to the nearest tenth) }\end{aligned}$[/tex]
