The only tools you need to make these shapes are a straight ruler and a compass or dividers (Figure 1). It is also useful to have a protractor (to measure angles) and a drafting square (to make square ...

When measuring angles: it is always the angle between the ray and the normal that is measured, a protractor is used. Remember to use a ruler and a sharp pencil.

Need to get a handle on a minuscule angle? All you need is your trusty plasmon nano-protractor, a new tool that can be used to do things like measure how DNA twists as it replicates. Created by ...