2. The Coordinate Plane The coordinate plane is formed when two number lines (called axis) intersect at right angles. The horizontal axis is called the x-axis and the vertical axis is called the y-axis.

3. The Coordinate Plane The axis intersect at the origin and divide the coordinate plane into four sections called quadrants. Quadrant IQuadrant II Quadrant IIIQuadrant IV origin

4. The Coordinate Plane An ordered pair of numbers identifies the location of a point. These numbers are the coordinates of the point. The coordinate of the origin is (0,0). A(-4,3) (0,0)

5. The Coordinate Plane Note that point A is 4 units to the left of the y-axis and also 3 units above the x-axis. A(-4,3) 1 2 3 4 1 2 3 The numbers –4 and 3 are called the coordinates of point A. The dot at A is the graph of the point with coordinates (- 4,3). x-coordinate y-coordinate

6. The Coordinate Plane Can you state the coordinates of the following points? A P B Q

7. The Coordinate Plane How did you do? A(5,3) P(-1,5) B (1,-2) (-4,-3) Q

8. The Distance Formula The distance between two points and is: The distance d between two points A (x 1,y 1 ) and B (x 2,y 2 ) is: B(x 2,y 2 ) (x 1,y 1 )A

9. In the next lesson, you be learning the basic tools of AutoCAD. AutoCAD normally only uses Quadrant 1 of the coordinate plane. A(5,3) P(-1,5) B (1,-2) (-4,-3) Q

10. In Quadrant 1, the X and Y coordinates of any number are both positive. Look at the coordinates indicator as you move your mouse around the AutoCAD screen. It shows you the X,Y,Z coordinates of the cursor. They should change as you move the cursor. (If the coordinates do not work, press the F6 key to activate them).

11. Objects you want to draw can be located accurately by typing in x and y coordinates. For objects like lines, you would specify endpoints.

12. Objects you want to draw can be located accurately by typing in x and y coordinates. For objects like circles, you would specify the coordinates of the center, and the radius or diameter.