use protractor in a sentence.
The plugin actually combines two libs, the Ribbon brush is used only for display (could be any brush if you switch out that class in the JS), meanwhile the points you draw are also tested against the Protractor gesture recognition algorithm.
I had a math(s) teacher when I was about 11, who would use the phrase "sit on your protractor" to talk about getting inside a geometry problem and asking yourself "does my solution roughly make sense".
Let me try another stab at figuring out why non Euclidean geometry took so long to arise: I'm under the impression that a large portion of Greek geometry was based on construction using a compass and protractor.
This isn't to say one should rely heavily on gut decisions, since that's likely to be self-defeating; on the other hand, you don't use a slide rule and protractor to drive.