An aeroplane flies from a town P(lat. 40°N, 38°E) to another town Q(lat. 40°N, 22°W). It later flies to a third town T(28°N, 22°W). Calculate the : (a) distance between P and Q along their parallel of latitude ; (b) distance between Q and T along their line of longitudes; (c) average speed at which the aeroplane will fly from P to T via Q, if the journey takes 12 hours, correct to 3 significant figures. [Take the radius of the earth = 6400km ; ]
Explanation
(a) Distance along arc PQ = where = (to the nearest whole number) (b) Difference in latitude between Q and T = 40° - 28° = 12° (c) Average speed = = (to 3 significant figures)
