### 2.4 Lines ¶

A line is internally represented by an origin point and an angular direction, i.e. the anticlockwise angle from the horizontal axis to the line. Thus, lines have an implicit orientation.

#### Line related functions ¶

`line(A, a)`

  Line of origin A and direction a.

`line(A, B)`

  Line of origin A, passing through point B.

`line(A, u)`

  Line of origin A, directed by vector u.

`line(s)`

  Line passing through segment s. The origin is set to the first point of s.

`parallel(l, A)`

  Parallel to line l of origin A.

`parallel(s, A)`

  Parallel to segment s of origin A.

`perpendicular(l, A)`

  Perpendicular to line l of origin A.

`perpendicular(s, A)`

  Perpendicular to segment s of origin A.

`bisector(l, l')`

  Bisector of lines l and l'. The resulting angular direction is the mean of the directions of l and l'.

`distance(A, l)`

  Distance between point A and line l.

`arg(l)`

  Polar angle of line l (in degrees).

`point(l, x)`

  Point of abscissa x on line l with respect to its implicit origin and orientation.

`abscissa(l, x)`

  Point of abscissa x on line l with respect to the implicit coordinate system.

`ordinate(l, y)`

  Point of ordinate y on line l with respect to the implicit coordinate system.

`vector(l)`

  Unit vector having the same direction than line l.