Geometry: Using compasses to draw a perpendicular line

Here we learn how to draw a perpendicular line using the compasses we use for drawing circles – that’s geometry for you!

 

 Lightly draw the first arc centred on point A

 

Then repeat the arc but centred on point B – with compasses set to the same radius as they were at A

 

Draw a line from one intersection to the other and it will be perpendicular to line AB

 

 

You can try another radius for the compasses but the result is the same!