Q11 An aeroplane leaves an airport and flies due north at a speed of 1000 km per hour. At the
same time, another aeroplane leaves the same airport and flies due west at a speed of
1200 km per hour. How far apart will be the two planes after 1 1/2 hours?
Distance travelled by the first aeroplane due north in hours.
Distance travelled by second aeroplane due west in hours.
OA and OB are the distance travelled.
By Pythagoras theorem,
Thus, the distance between the two planes is .