Drawing infinite lines

Infinite lines are sometimes referred to as construction lines. An infinite line is a line through a given point, oriented at a specified angle in three-dimensional space and extending to infinity in both directions. Because infinite lines extend to infinity, they are not calculated as part of the drawing extents.

The default method for drawing an infinite line is to select a point along the line and then specify the direction of the line. You can draw an infinite line in any of the following ways:

Horizontal draws the infinite line parallel to the x-axis of the current UCS.
Vertical draws the infinite line parallel to the y-axis of the current UCS.
Angle draws the infinite line parallel to a specified angle.
Bisect draws the infinite line perpendicular to an existing entity.
Parallel draws the infinite line parallel to an existing entity.

To draw an infinite line

Do one of the following to choose Infinite Line:
On the ribbon, choose Home > Infinite Line or choose Draw > Infinite Line.
On the menu, choose Draw > Infinite Line.
On the Draw toolbar, click the Infinite Line tool.
Type infline and then press Enter.
Specify a point along the line.
Specify the direction.
To complete the command, press Enter.

You can also draw infinite lines at a specific angle or at an angle relative to an existing entity.

To draw an infinite line at a specified angle relative to another entity

Do one of the following to choose Infinite Line ( ):
On the ribbon, choose Home > Infinite Line or choose Draw > Infinite Line.
On the menu, choose Draw > Infinite Line.
On the Draw toolbar, click the Infinite Line tool.
Type infline and then press Enter.
In the prompt box, choose Angle.
In the prompt box, choose Reference.
Select the reference entity.
Specify the angle of the infinite line in relation to the selected entity.
Specify the location of the infinite line.
To complete the command, press Enter.