Given a line L in the projective plane, what is its dual point?

The line L(0 ), however, has returned to itself as L(180 ) "'pointed in the opposite direction"'.

These are precisely the affine transformations with the property that the image of every line L is a line parallel to L.

The line L is called the axis, center, or base line of the hypercycle.

However, if a line L does not intersect its circle C for some k, there is no pair of solutions for that homothetic-center line.

Given a point p and a line l, there is a unique fold perpendicular to l that passes through point p.

This has the effect of reflecting the plane in the line L, called the reflection axis or the associated mirror.

This is a combination of a reflection in the line L and a translation along L by a distance d.

Point P is called the pole of the neusis, line l the directrix, or guiding line, and line m the catch line.

As with line H, line K experienced strong demand, which led to the opening of line L on 8 January 1962.