Pole: If the tangent of the curve tangent to two points A and B intersect at point P, then point P is called the pole of straight line AB relative to the curve, and straight line AB is called the polar line of point P. The idea of pole and polar line is the generalization of the idea that a point and a tangent on the curve pass through this point. Any point has a polar line relative to the general algebraic curve, and every straight line has a pole. If the point is on this curve, then the polar line.

Polar line: Mathematically, if the tangent of a curve and two points A and B intersect at point P, then point P is called the pole of straight line AB about the curve, and straight line AB is called the polar line of point P. The idea of pole and polar line is a summary of the idea that a point and a tangent on the curve pass through this point. Any point of a general algebraic curve has a polar line, and every straight line has a pole. If the point is on this curve,