Autodesk AUTOCAD 2006 Command Reference Manual page 345

angle vertex
Line Selection
Defines the angle using two lines.
Select second line:
The program determines the angle by using each line as a vector for the angle
and the intersection of the lines for the angle vertex. The dimension line spans
the angle between the two lines. If the dimension line does not intersect the
lines being dimensioned, extension lines are added as needed to extend one
or both lines. The arc is always less than 180 degrees.
angle displayed depends
on cursor position
Three-Point Specification
Creates a dimension based on three points you specify.
Specify angle vertex: Specify a point (1)
Specify first angle endpoint: Specify a point (2)
Specify second angle endpoint: Specify a point (3)
The angle vertex can be the same as one of the angle endpoints. If you need
extension lines, the endpoints are used as origin points.
2
1
3
The dimension line is drawn as an arc between the extension lines. The
extension lines are drawn from the angle endpoints to the intersection of the
dimension line.
Viewpoint Presets Dialog Box | 321