The Cartesian PLane

1. The Cartesian PLane • Let’s start graphing!

2. Introduction to x-y plane You learned about the basic (counting) number line back in elementary school: Later on, you were introduced to zero and negatives, which completed the number line:

3. Descartes' breakthrough was in taking a second number line, standing it up on its end, and crossing the first number line at zero:

4. Ordered Pairs An 'ordered pair' is simply two numbers in a certain order. For example, the numbers '2' and '3' can form two ordered pairs: 2, 3       and      3, 2 In mathematics, we use two numbers to accurately locate a position on a rectangular grid, like this:

5. Coordinate system On a graph grid, the point (0,0) is called the 'origin' y coordinate origin The first coordinate of a plotted point is called the 'x' coordinate X coordinate The second coordinate of a plotted point is called the 'y' coordinate

6. (2, 4) (-4, 3) (-5, -4) (3, -3) ● ● ● ● Let’s Graph 2 1 ● ● (2, 4) (-4, 3) (-5, -4) (3, -3) ● ● 3 4

7. (1, 5) 2 1 (2, -3) (-2, -1) (5, -5) 3 4 (-2, 1) Your turn: which quadrant will the point lie? 1 ● 4 ● 3 ● ● 4 ● 2