The polar line is the locus of the intersections of tangent lines at the ends of chords of teh parabola through a fixed point.
Turns out to be conceptually important - not just a curiosity.
The polar point of a line in an ellipse is a common point to the chords defined by the common tangents through the points on the line.
Play with it and the meaning will be clear!
(Go to Full Screen if the green points won't drag)
The polar point of a line in a parabola is a common point to the chords defined by the common tangents through the points on the line.
(Go to Full Screen if the green points won’t drag)
The locus of the intersection of tangents at the ends of chords of a parabola through a given fixed point is a straight line.
This is called the polar line of the given point
The locus of the intersections of the tangents at the end of chords of an ellipse which pass through a common point is a straight line.
A bit of a mouthful, but play with the diagram and it will become clear.