The better that I know plane and cartesian Geometry, the better that I can both script, and draw (using a free open-source suite like Inkscape) computer Graphics.
In Plane Geometry, a straight edge is used. A straight edge differs from a ruler, in that:
- whereas rulers possess gradated markings that indicate standard units of measurement, there are no gradated markings that indicate standard units of measurement – such as millimeters centimeters, etc. – on a straight edge.
- the width of the straight edge is deemed infinite, whereas real-life rulers are, it is needless to say, of finite width.
Figure 1: A collapsible compass and straight edge. These two instruments are employed in the construction of figures in Euclidean Geometry. The span of a collapsible compass is deemed to collapse, should both the metallic point, and the graphite point of the compass be removed at the same time from the page.
See the Pen Collapsible Compass and Straight Edge Inkscape SVG by Ciaran Mc Ardle (@Valerius_de_Hib) on CodePen.
Maths and Comedy 