Transcript 9-1 Ordered Pairs

9-1 Ordered Pairs
Presented by Mrs. Spitz
Fall 2006
Objective

After studying this lesson, you should be
able to graph ordered pairs on a
coordinate plane.
Assignment

pg. 357 #5-57 all
Application

Mrs. Spitz makes seating charts for her
classes. Her classroom has 4 rows of
desks with 7 desks in each row. She
assigns desks by using two numbers. The
first number is for the row of the desk and
the second number is for the desk in that
row. Mrs. Spitz assigns (3, 2) to Christina
and (2, 3) to Jasmine. This means
Christina will sit in the third row at the
second seat and Jasmine will sit in row 2
at the third seat.
Graphic
Jasmine
Christina
Notice that (3,2) and (2, 3) do not name
the same desk in the seating chart. (3,2)
and (2,3) are called ordered pairs because
the order in which the pairs are written is
important.
 Ordered pairs are used to locate points in
a plane. The points are in reference to
two perpendicular lines at which the
number lines intersect called the ORIGIN

Some definitions
Perpendicular lines are lines that meet to
form 90º angles.
 Origin—the point where the X-axis and yaxis meet (0,0).
 X-axis—the horizontal axis
 Y-axis—the vertical axis
 Coordinate plane—the plan that contains
the x and y axis

Some more information

The first number, or coordinate, or an
ordered pair corresponds to a number on
the x-axis. The second number of an
ordered pairs, corresponds to the y axis.
To find the ordered pair for A, shown in
the next graphic, thnk of a horizontal and
a vertical line passing through point A.
Points on a Coordinate Plane
The coordinate plane
is divided into 4
quadrants
 Each quadrant has
the first number
either positive or
negative as well as
the second positive or
negative. Look to see
which is which.

Quadrant II
(-, +)
Quadrant I
(+,+)
Quadrant III
(- , -)
Quadrant IV
(+, -)
Points on a Coordinate Plane
Imagine a point @
the origin (0,0). Now
draw a point that is at
(-2.-3) and (3, 2)
 Where is point A
located? Point B?
Point C? Point D?

C
A
D
B
Points on a Coordinate Plane
Plot the following
point—(3,1)
 Start at the origin
(0,0) and move 3
units to the right.
Then move one unit
up and draw a dot.
Label this E.

C
A
D
B
Points on a Coordinate Plane
Plot the following
point—(3,1)
 Start at the origin
(0,0) and move 3
units to the right.
Then move one unit
up and draw a dot.
Label this E.

C
A
E
D
B
Points on a Coordinate Plane
Plot the following
point—(-3,-2)
 Start at the origin
(0,0) and move 3
units to the left since
it’s negative. Then
move one unit down
and draw a dot.
Label this F.

C
A
D
B
Points on a Coordinate Plane
Plot the following
point—(-3,-2)
 Start at the origin
(0,0) and move 3
units to the left since
it’s negative. Then
move one unit down
and draw a dot.
Label this F.

C
F
A
D
B
Completeness Property for
Points in a Plan
1.
2.
Exactly one point in a plane is named by
a given ordered pair of numbers.
Exactly one ordered pair of numbers
names a given point in a plane.
You need:
Graph paper
 Ruler /straight edge
 colored pencil (to mark different lines)
 http://www.taosschools.org/ths

 Go
to Departments|Math for graph paper that
is already lined and made up. I won’t provide
it unless it’s easy. You go print it.