Impossible constructions: Trisecting an angle.

We had a look at some models for algebra, geometry and trigonometry from school mathematics. Now, models for those results which we do not normally come across in formal study, but math-lovers would be greatly interested in, shall be taken up, of course, with models. Presented here, by Hema Vasavada, is a demonstration of a model for a mechanical construction of a mathematically impossible construction, that of trisecting an angle.