1. EDT 310 - Chapter 41 Coordinate Systems Cartesian, Relative and Polar Sacramento City College EDT 310

2. EDT 310 - Chapter 42 Point Entry Mode u Each of the point entry methods uses the Cartesian coordinate system. u The Cartesian coordinate system is based on selecting distances from three intersecting axes, X, Y, and Z. u A location is defined by its distance in x,y from the origin point. u Most of our work will be in 2D not 3D.

3. EDT 310 - Chapter 43 The Cartesian Coordinate System u The Origin divides the coordinate system into four quadrants. u Points are located in relation to the origin. u The Origin is point 0,0 and is the location where the X and Y axes cross. u For AutoCAD, the origin is the lower-left of your drawing.

4. EDT 310 - Chapter 44 Origin (0,0) Quadrant 1

5. EDT 310 - Chapter 45 The Cartesian Coordinate System Quadrant #1 +x, +y Quadrant #3 -x, -y Quadrant #2 -x, +y Quadrant #4 +x, -y Origin (0,0)

6. EDT 310 - Chapter 46 Using Absolute Coordinates u Points are measured from the origin. u A point [4,2] is u 4 units in the X direction. u 2 units in the Y direction. u from the origin. u The coordinate display on the lower left corner of the screen shows the location of the cursor at any time.

7. EDT 310 - Chapter 47 Using Absolute Coordinates u You can draw lines by typing in the coordinates of the line. u Command: L or LINE u Specify first point: 4,2 u Specify next point or [Undo]: 7,2 u Specify next point or [Undo]: 7,6 u Specify next point or [Undo]: 4,6 u Specify next point or [Undo]: 4,2 u Specify next point or [Undo]: [Enter] u Command:

8. EDT 310 - Chapter 48 Using Relative Coordinates u Relative coordinates are located from the previous position, rather than from the origin. u The “@” symbol must precede each entry.

9. EDT 310 - Chapter 49 Using Relative Coordinates u Command: u Specify first point: 2,2 u Specify next point or [Undo]: @6,0 u Specify next point or [Undo]: @2,2 u Specify next point or [Undo]: @0,3 u Specify next point or [Undo]: @-2,2 u Specify next point or [Undo]: @-6,0 u Specify next point or [Undo]: [Enter] u Command:

10. EDT 310 - Chapter 410 Using Polar Coordinates u A point located using polar coordinates is based on u the distance from a fixed point (@6 u at a given angle (< 45) u Procedure: u Enter the distance u then u Enter the angle u Example: @6<45

11. EDT 310 - Chapter 411 Using Polar Coordinates u The angular values used for polar coordinates are: u 0 = east (or to the right) u 90 = North (or up) u 180 = West (or to the left) u 270 = South (or down).

12. EDT 310 - Chapter 412 Using Polar Coordinates u @4<45 means u Measure from the previous point u A distance of 4 u At an angle of 45 degrees from 0 degrees.

13. EDT 310 - Chapter 413 The Coordinate Display

14. EDT 310 - Chapter 414 The Coordinate Display u The coordinate display shows the current cursor location. u Turn the cursor tracking display on and off with the [F6] key.

15. EDT 310 - Chapter 415 The COORDS Variable u The COORDS variable lets you choose how the coordinates will be displayed. u 0 = the coordinate display is static. Coordinates are displayed only when points are selected. u 1 = the coordinate display is dynamic. u 2 = the coordinate display is in polar mode showing length at an angle.