7. Five mark example problem I

An Aeroplane leaves an airport and flies due north at a speed of 1000 $km/hr$. At the same time, another aeroplane leaves the same airport and flies west at a speed of 1200 $km/hr$. How far apart will be the two planes after $1\frac{1}{2}$ hours?

 

The distance between two aeroplanes after $1\frac{1}{2}$ hours $=$ $i\sqrt{i}\mathit{km}$

 

The theorem used to find the distance between two aeroplanes $=$ Thales theoremPythagoras theoremSimilar trianglesAngle bisector theorem