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Internet references

Wikipedia: Cubic_function — Cardano's method Cardano's method of solving cubic polynomials

Ken Ward's math pages: Cardano's Method Examples

Related pages in this website

Click here for more information about this curious phenomenon.

Quadratic formula

Quartic formula - Ferrari's method of solving a quartic equation

Trig Functions of Special Angles, part 2 -- in this page, we look at a fun problem involving cos 40�, cos 80�, and cos 160�.  It turns out these three cosines are the roots of 8x³-6x+1=0.  Since these three roots are all real, the cubic formula doesn't work without complex numbers, but it does work, and it finds all three roots.


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