The problem involves calculating distances and times for an aeroplane traveling between several towns on Earth. We will use the Earth's radius R_E = 6370 km where necessary, and the defini

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The problem involves calculating distances and times for an aeroplane traveling between several towns on Earth. We will use the Earth's radius $R_E = 6370 \, \text{km}$ where necessary, and the definition of a nautical mile (1 NM = 1 minute of arc along a great circle).

a) Calculate the distance from A to B in nautical miles.
Town A: $L_A = 72^\circ N$, $\lambda_A = 60^\circ W$
Town B: $L_B = 55^\circ N$, $\lambda_B = 20^\circ E$
The shortest route is along a great circle. The angular separation $\theta$