If and are two points on the curve, then we can uniquely describe a third point in the following way. First, draw the line that intersects and . This will generally intersect the cubic at a third point, . We then take to be , the point opposite .
If and are two points on the curve, then we can uniquely describe a third point in the following way. First, draw the line that intersects and . This will generally intersect the cubic at a third point, . We then take to be , the point opposite .