2004

222 | Chapter 15 Use Precision Tools
When you need to define a point based on a previous point, you can enter a
relative spherical coordinate by preceding it with the @ sign.
To enter spherical coordinates
At a prompt for a point, enter the coordinate values using the following
format:
x<[angle from X axis] <[angle from XY plane]
■ X represents the distance from the UCS origin (0,0,0).
■ Angle from X axis represents the angle from the X axis in the XY plane.
■ Angle from XY plane represents the angle from the XY plane.
For example, 4<60 <60 represents a location that is 4 units from the UCS ori-
gin measured at 60 degrees from the positive X axis in the XY plane and at
60 degrees from the XY plane.
Control the User Coordinate System (UCS) in
2D
In AutoCAD , there are two coordinate systems: a fixed system called the
world coordinate system (WCS), and a movable system called the user
coordinate system (UCS). In the WCS, the X axis is horizontal, the Y axis is
vertical, and the Z axis is perpendicular to the XY plane. The origin is where
the X and Y axes intersect (0,0) in the lower-left corner of the drawing. You
define a UCS in terms of the WCS. Virtually all coordinate entry uses the
current UCS.
Moving the UCS can make it easier to work on particular sections of your
drawing. Rotating the UCS helps you specify points in three-dimensional or
rotated views. Snap, Grid, and Ortho modes all rotate in line with the new
UCS.
You can relocate the user coordinate system using any of these methods:
■ Move the UCS by defining a new origin.
■ Align the UCS with an existing object or with the current viewing
direction.