Answer
$a=288\;km$.
$c=890\;km$.
Work Step by Step
The given values are
$b=841.6\;km$
$A=18.91^{\circ}$.
By using trigonometric ratios in the figure Illustration 1.
$\frac{b}{c}=\cos{A}$
Isolate $c$.
$c=\frac{b}{\cos{A}}$
Plug all values.
$c=\frac{841.6\;km}{\cos{18.91^{\circ}}}$
Simplify (Use degree calculator).
$c=890\;km$ (rounded value).
By using trigonometric ratios in the figure Illustration 1.
$\frac{a}{b}=\tan{A}$
Isolate $a$.
$a=b\cdot \tan{A}$
Plug all values.
$a=(841.6\;km)⋅tan(18.91^{\circ})$
Simplify (Use degree calculator).
$a=288\;km$ (rounded value).
