Notes on Some Geometric and Algebraic Problems Solved by Origami
  Details for known solutions of some geometric and algebraic problems with the help of origami are presented: two theorems of Haga, the general cubic equation, especially the heptagon equation, doubling the cube as well as the trisection of angles $\alpha$, $\pi - \alpha$ and $\pi + \alpha$. 
Wolfdieter Lang
math.MG