Using two-dimensional coordinates

When working in two dimensions, you specify points on the xy plane. You can specify

any point as an absolute coordinate (or Cartesian coordinate), using the exact xcoordinate and y-coordinate locations in relation to the origin (the 0,0 coordinate

point at which the two axes intersect), or as a relative coordinate in relation to the previous

point. You can also specify points using relative or absolute polar coordinates, which locate a point using a distance and an angle.

Entering absolute Cartesian coordinates

To enter absolute Cartesian coordinates, type the coordinate location of the point in

the command bar. For example, to use absolute Cartesian coordinates to draw a line

from the origin (0,0) to a point 3 units to the right and 1 unit above the origin, start the

Line command and respond to the prompts as follows:

Start of line: 0,0

Angle • Length • <Endpoint>: 3,1

When using absolute Cartesian coordinates, you need to know the exact point locations

for anything you draw. For instance, to use absolute Cartesian coordinates to

draw an 8.5-unit square with its lower left corner at 4,5, you must determine that the

upper left corner is at coordinate 4,13.5, the upper right corner at 12.5,13.5, and the

lower right corner at 12.5,5.

Entering relative Cartesian coordinates

Another, simpler method is to use relative Cartesian coordinates: you specify a location

in the drawing by determining its position relative to the last coordinate you specified. To use relative Cartesian coordinates, type the coordinate values in the command bar, preceded

by the at symbol (@). The coordinate pair following the @ symbol represents the distance along the x-axis and the y-axis to the next point. For example, to draw an 8.5-unit square with its lower left corner at 4,5 using relative Cartesian coordinates, start the Line command, and then respond to the prompts as follows:

Start of line: 4,5

Angle • Length • <Endpoint>: @8.5,0

Angle • Length • Follow • Undo • <Endpoint>: @0,8.5

Angle • Length • Follow • Close • Undo • <Endpoint>: @-8.5,0

Angle • Length • Follow • Close • Undo • <Endpoint>: C

The first relative coordinate (@8.5,0) locates the new point 8.5 units to the right (along the x-axis) from the previous point of 4,5; the second relative coordinate (@0,8.5) locates the next point 8.5 units above (along the y-axis) the previous point, and so on. Entering C (for Close) draws the final line segment back to the first point specified when you started the Line command.

Entering polar coordinates

Using relative polar coordinates makes drawing a square tilted at a 45-degree angle a simple task. Polar coordinates base the location of a point on a distance and angle from either

the origin (absolute coordinate) or from the previous point (relative coordinate).

To specify polar coordinates, type a distance and an angle, separated by the open angle bracket (<). For example, to use relative polar coordinates to specify a point 1 unit away from the previous point and at an angle of 45 degrees, type @1<45.

To draw the square from the example in the previous section, “Entering relative Cartesian coordinates,” this time tilted at a 45-degree angle, start the Line command, and then respond to the prompts as follows:

Start of line: 4,5

Angle • Length • <Endpoint>: @8.5<45

Angle • Length • Follow • Undo • <Endpoint>: @8.5<315

Angle • Length • Follow • Close • Undo • <Endpoint>: @8.5<225

Angle • Length • Follow • Close • Undo • <Endpoint>: C

This example assumes the program’s default settings.

Like all examples in this guide, the example assumes default settings: Angles increase

counterclockwise and decrease clockwise. An angle of 315 degrees is the same as -45

degrees.