An aeroplane leaves an airport and flies due north at a speed of 1000 km per hour. At thesame time, another aeroplane leaves the same airport and flies due west at a speed of1200 km per hour. How far apart will be the two planes after
hours?
Distance travelled by the plane flying towards north in
= 1,000 * 
= 1,500 km
Similarly, distance travelled by the plane flying towards west in 
= 1,200 * 
= 1,800 km
Let these distances be represented by OA and OB respectively.
Applying Pythagoras theorem,
Distance between these planes after
, AB = 
= (
km
= 
km
= 
km
= 
km
= 300
km
12