Question

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
1
1200 km per hour. How far apart will be the two planes after
hours?
​

Answer 1

The first aeroplane leaves an airport and flies due north at a speed of 1000 km per hr.

∴ Distance travelled in 1.5 hrs.

=1000×1.5=1500 km

Similarly, Distance traveled by second aeroplane,

=1200×1.5=1800 km

In △ABC,

BC is distance travelled by first aeroplane and BA is the distance traveled by second aeroplane.

Hence, applying Pythagoras Theorem,

AC

2

=AB

2

+BC

2

∴ AC

2

=1500

2

+1800

2

∴ AC=300

61

km

Hence, two planes are 300

61

km apart