posted by kudu .
A plane flying at 200 knots left an airport A( 30° S, 31°E) and flew due North to an airport B( 30° N 31° E)
(a) Calculate the distance covered by the plane, in nautical miles
(b) After a 15 minutes stop over B, the plane flew west to an airport C(30°N 13°E) at the same speed.
since both A and B are at the same longitude, they are separated by 60° latitude = π/3
the distance s = Rθ
where R is the radius of the earth.
If the plane flies to C along the 30° latitude line, it flies along a circle with radius Rcos30°, through an angle of 18° = π/10