(a)



Longitude difference = 85° - 25° = 60°.
Distance AB along the parallel of latitude = \(\frac{\theta}{360°} \times 2\pi R \cos \alpha\)
\(AB = \frac{60}{360} \times 2 \times \frac{22}{7} \times 6400 \cos 53\)
= \(\frac{1}{6} \times \frac{44}{7} \times 3851.62\)
= \(4,035.03 km\)
\(\approxeq 4035 km\)
(b) \(Speed = \frac{Distance}{Time}\)
\(\therefore Time = \frac{Distance}{Speed}\)
= \(\frac{4035}{400}\)
\(\approxeq 10 hours\).
(c) Distance BC measured along the meridian
\(BC = \frac{\theta}{360} \times 2 \pi R\)
\(2000 = \frac{\theta}{360} \times 2 \times \frac{22}{7} \times 6400\)
\(\theta = 17.898° \approxeq 18°\)
\(\theta\) = Latitude difference
Let the latitude of C = x.
\(\theta = 53 - x\)
\(18 = 53 - x\)
\(x = 35°\)