A Cubic Solution of Omar Khayyam
In the 11th century, Omar Khayyam classified all known cubics and gave geometric solutions for them.
Shown here is one of his simpler cases, the solution of a cubic plus sides (linear term) equal to a number.
Amazingly, Khayyam did not have graphing to do this, but constructed his parabolas geometrically.
Luckily we have GeoGebra!
If you want to dig deeper into the algebra, the parabola is and the circle is