Coordinates
- 1. Coordinate Geometry You should know what these mean and be able to use them: Coordinates Ordered pairs X axis Y axis
- 2. Start with a number line: 0 1 2 3 4 5 6 7 8 9 10 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
- 3. Add a vertical number line: 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7
- 4. The horizontal number line is called the “ x axis ” | | | | | | | | | | | | | | | | | | | | | -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
- 5. The vertical number line is called the “ y axis ” 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- (I remember y is for the up and down axis because the y stretches down.)
- 6. Put them together! | | | | | | | | | | | | | | | | | | | | | -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 --4 --3 --2 --1 -- -1 -- -2 -- -3 -- -4 -- -5
- 7. Where the two meet is called the “ origin ” That is zero on both scales. 0
- 8. It’s easier to find where you are if you put this on a grid: -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 7 6 5 4 3 2 1 -1 -2 -3 -4 -5 -6 -7 y x
- 9. Coordinates are the points on the grid: 2, 5 1, 3 3, 7 and so forth
- 10. We put the point at the coordinates--Start with X, then Y -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 7 6 5 4 3 2 1 -- -1 -- -2 -- -3 -- -4 -- -5 -- -6 -- -7 y x For example for 2,5 Go to 2 on the x axis first. Then go to 5 on the y axis. Here is the point defined as 2,5
- 11. The two coordinates come in pairs to tell you the point on the grid. They are an ordered pair. What’s the order? Which is first, x or y?
- 12. How do I remember which comes first, x or y? a b c d e f g h i j k l m n o p q r s t u v w x y z When you say or write the alphabet x comes before y
- 13. You can also think of running before you climb up or down