1. The Coordinate Plane 101 ALGEBRA 11/16/15

2. The coordinate plane is a set of axis on which ordered pairs of input and output values can be plotted.

3. Parts of the Coordinate Plane The origin is where the horizontal and vertical axes cross. This is the point (0,0) The horizontal axis is called the x-axis. The vertical axis is called the y-axis.

4. Parts of the Coordinate Plane Origin : (0,0) Y-Axis X-Axis

5. X-Axis Basics The x-axis works the same as a typical number line with zero at the origin. All points to the left of the origin have a negative x-value, and all points to the right of the origin have a positive x-value. +- Origin : (0,0)

6. Y-Axis Basics The y-axis serves as a vertical number line with zero at the origin. All points below the origin have a negative y-value, and all points above the origin have a positive y- value. + - Origin : (0,0)

7. Each point in a coordinate plane corresponds to an ordered pair. (x, _) (_, y) (9, 4) The first number in the ordered pair is the x-value or input value. The second number in the ordered pair is the y-value or output value. (X, Y)

8. Plotting Ordered Pairs Just like when we read, we plot ordered pairs first by where it is left to right. -Find the first number’s place on the x-axis Then, we plot the second number by where it is up to down. -Find the second number’s place on the y-axis For Example: Plot the point (-4,3)

9. The x-axis and y-axis divide the plane into four regions, called Quadrants. These Quadrants are defined by the positive and/or negative x and y values in the ordered pair. Coordinate Plane Quadrants

10. (+x, +y) (-x, -y) (-x, +y) (+x, -y)

11. Can a point be on an axis? Yes, if a point is on an axis, either the x-value or y-value must be ZERO. If a point is on an axis, how do I know the quadrant it’s in? If a point lies directly on either axis, it is not considered to be in a quadrant.