Using the Pythagorean Theorem we get:
[tex]c^2=a^2+b^2\text{.}[/tex]Therefore:
[tex]b^2=c^2-a^2\text{.}[/tex]Substituting a=200.7km and c=401.5km we get:
[tex]b^2=(401.5km)^2-(200.7km)^2.[/tex]Solving the above equation for b we get:
[tex]\begin{gathered} b=\sqrt[]{(401.5km)^2-(200.7km)^2} \\ =\sqrt[]{161202.25km^2-40280.79km^2} \\ =\sqrt[]{120921.76km^2}\approx347.74km\text{.} \end{gathered}[/tex]Now, from the given diagram we get that:
[tex]\begin{gathered} \cos B=\frac{a}{c}, \\ \sin A=\frac{a}{c}\text{.} \end{gathered}[/tex]Substituting a=200.7km and c=401.5km we get:
[tex]\begin{gathered} \cos B=\frac{200.7\operatorname{km}}{401.5\operatorname{km}}=\frac{2007}{4015}\text{.} \\ \sin A=\frac{200.7\operatorname{km}}{401.5\operatorname{km}}=\frac{2007}{4015}\text{.} \end{gathered}[/tex]Therefore:
[tex]\begin{gathered} B=\cos ^{-1}(\frac{2007}{4015})\approx60.00^{\circ}, \\ A=\sin ^{-1}(\frac{2007}{4015})\approx30.00^{\circ}, \end{gathered}[/tex]Answer:
[tex]\begin{gathered} b=347.74\operatorname{km}, \\ B=60.00^{\circ}, \\ A=30.00^{\circ} \end{gathered}[/tex]