Editing Ruler (section)

== Use in geometry ==
{{Main article|Compass and straightedge}}

In geometry, straight lines between points may be drawn using a straightedge (ruler without any rules on it). Furthermore, it is also used to draw accurate graphs and tables.

A [[compass and straightedge|ruler and compass construction]] is a construction that uses a ruler and a compass. It is possible to bisect an angle into two equal parts with a ruler and compass. It can be proven, though, that it is impossible to divide an angle into three equal parts using only a compass and straightedge&nbsp;— the problem of [[angle trisection]]. However, if two marks be allowed on the ruler, the problem becomes solvable via a [[neusis]] construction.