An aeroplane takes off from 30° North Latitude, 50° East Longitude, and lands at the opposite end of the earth. Where does it land?

Answer: (d) 30° South Lat., 130° West Long

Antipode: latitude 30°S; longitude 180° − 50° = 130°W.

The idea

An antipode lies directly opposite a point through Earth’s centre. Its latitude has the same magnitude in the other hemisphere. Its longitude is 180° away, with east and west exchanged for the usual non-zero, non-180° coordinates.

Draw a line from the starting point through Earth’s centre → Reverse the latitude hemisphere → Keep the latitude magnitude → Subtract the longitude magnitude from 180° → Use the opposite east/west label

Why the others are wrong

(a) Only flips the longitude — still in the northern hemisphere.

(b) Flips both but uses 50°W instead of 130°W.

(c) Swaps the numbers.

The trap

(b) looks symmetrical, but longitude must shift by 180°.

Elimination technique

The latitude must remain 30° but change to south, so remove (a) and (c). The longitude must also change by 180°, which separates (b) from (d).

Also know

Antipodes are separated by half a great circle along Earth’s surface. Every great circle divides a sphere into equal halves; meridians paired with their opposite meridians form great circles. The equator is a great circle, while other parallels of latitude are smaller circles.