Solving a Cubic via the Trisection of an Angle
This Demonstration shows a geometric solution to the equation , where and are real in the case where the equation has three distinct real roots (i.e. has a positive discriminant). It is based on Viète's trigonometric solution of the cubic that constructs and trisects a particular angle associated with the given cubic equation.
For a detailed discussion of the trigonometric solution to the cubic, see  or .
 G. E. Martin, Geometric Constructions, New York: Springer–Verlag, 1998 p. 132–133.
 D. A. Cox, Galois Theory, New York: John Wiley & Sons, 2004 p. 18–19.