Ordered Pairs

Graphing on the Coordinate Plane

Vocabulary

• coordinate plane• axes• x-axis• y-axis• origin• Coordinates (ordered pair)• x-coordinate• y-coordinate

Coordinate Plane

A coordinate plane is formed by two number lines in a plane that intersect at right angles. The point of intersection is the zero on each number line.

Coordinate Plane

• The two number lines are called the axes.

A coordinate plane is formed by two number lines in a plane that intersect at right angles. The point of intersection is the zero on each number line.

• The horizontal axis is called the x-axis.

A coordinate plane is formed by two number lines in a plane that intersect at right angles. The point of intersection is the zero on each number line.

• The vertical axis is called the y-axis.

A coordinate plane is formed by two number lines in a plane that intersect at right angles. The point of intersection is the zero on each number line.

• The point where the axes intersect is called the origin.

An ordered pair gives the location of a point on a coordinate plane. The first number tells how far to move right (positive) or left (negative) from the origin. The second number tells how far to move up (positive) or down (negative).

The numbers in an ordered pair are called coordinates. The first number is called the x-coordinate. The second number is called the y-coordinate.

The ordered pair for the origin is (0,0).

Click on the picture to see an example

Example 1: Naming Points Using Ordered Pairs

Write the ordered pair that names point B.Step 1 Start at the origin. Move right along the x-axis until you are under point B. The x-coordinate of the ordered pair is 5.Step 2 Now move up until you reach point B. The y-coordinate is 6.So, point B is named by the ordered pair (5, 6).

O 2 4 6 8 x

Y

8

6

4

2

B

●

O 2 4 6 8 x

Y

8

6

4

2

●

●

●

●

RAFFLE Mr. King’s class is conducting a raffle to raise money for a local charity organization. The costs of 1, 2, 3, and 4 raffle tickets are shown in the table. List this information as ordered pairs (number of tickets, cost). The ordered pairs are (1, 1.5), (2, 3), (3, 4.5), and (4, 6).

Raffle Tickets

Number of Tickets

Cost ($)

1 1.5

2 3

3 4.5

4 6

Real World Example

The points appear to fall on a line.

4-9 Study Guide ExercisesUse the coordinate

plane at the right to name the ordered pair for each point.

• 1. J• 2. K• 3. L• 4. M

Graph and label each point on the coordinate plane.

• 5. S(1, 3) 6. T(4, 0)