coordinate geometry shirley sides. 2006. definition grid – a pattern of horizontal and vertical...

Coordinate GeometryCoordinate Geometry

Shirley Sides.Shirley Sides.

20062006

DefinitionDefinition• Grid – A pattern of horizontal

and vertical lines, usually forming squares.

DefinitionDefinition• Coordinate grid – a grid used to

locate a point by its distances from 2 intersecting straight lines.

1

32

45

0

6

1 2 3 4 50 6

DefinitionDefinition• x axis – a horizontal number

line on a coordinate grid.

1 2 3 4 50 6 x

HintHint• x ‘is a cross’

(across )

1 2 3 4 50 6 x

DefinitionDefinition• y axis – a vertical number line

on a coordinate grid.

12345

0

6

y

DefinitionDefinition• Coordinates – an ordered pair

of numbers that give the location of a point on a grid. (3, 4)

12345

0

6

1 2 3 4 50 6

(3,4)

HintHint• The first number is always the x or first letter

in the alphabet. The second number is always the y the second letter in the alphabet.

1

32

45

0

6

1 2 3 4 50 6

(3,4)

How to Plot Ordered PairsHow to Plot Ordered Pairs• Step 1 – Always find the x value

first, moving horizontally either right (positive) or left (negative).

1

32

45

0

6

1 2 3 4 50 6

(2, 3)

y

x

How to Plot Ordered PairsHow to Plot Ordered Pairs• Step 2 – Starting from your new position

find the y value by moving vertically either up (positive) or down (negative).

1

32

45

0

6

1 2 3 4 50 6

(2, 3)(2,3)y

x

How to Find Ordered PairsHow to Find Ordered Pairs• Step 1 – Find how far over horizontally

the point is by counting to the right (positive) or the left (negative).

1

32

45

0

6

1 2 3 4 50 6

(5, 4)

y

x

How to Find Ordered PairsHow to Find Ordered Pairs• Step 2 – Now count how far

vertically the point is by counting up (positive) or down (negative).

1

32

45

0

6

1 2 3 4 50 6

(5,4)

y

x

What is the ordered pair?What is the ordered pair?

1

32

45

0

6

1 2 3 4 50 6

(3,5)

y

x

What is the ordered pair?What is the ordered pair?

1

32

45

0

6

1 2 3 4 50 6

(2,6)

y

x

What is the ordered pair?What is the ordered pair?

1

32

45

0

6

1 2 3 4 50 6

(4,0)

y

x

What is the ordered pair?What is the ordered pair?

1

32

45

0

6

1 2 3 4 50 6

(0,5)

y

x

What is the ordered pair?What is the ordered pair?

1

32

45

0

6

1 2 3 4 50 6

(1,1)

y

x

Four Quadrants GridFour Quadrants Grid• When the number lines are extended into

the negative number lines you add 3 more quadrants to the coordinate grid.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

y

x

Four Quadrants GridFour Quadrants Grid• If the x is negative you move

to the left of the 0.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

x = -2y

x

Four Quadrants GridFour Quadrants Grid• If the y is negative you move

down below the zero.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

y = -3y

x

How to Plot in 4 QuadrantsHow to Plot in 4 Quadrants• Step 1 - Plot the x number first

moving to the left when the number is negative.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-3, -2)(-3, -2)y

x

How to Plot in 4 QuadrantsHow to Plot in 4 Quadrants• Step 2 - Plot the y number moving

from your new position down 2 when the number is negative.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-3, -2)(-3, -2)

y

x

How to Plot in 4 QuadrantsHow to Plot in 4 Quadrants• When x is positive and y is

negative, plot the ordered pair in this manner.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(2, -2)(2, -2)

y

x

How to Plot in 4 QuadrantsHow to Plot in 4 Quadrants• When x is negative and y is

positive, plot the ordered pair in this manner.

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-2, 2)(-2, 2)

y

x

Plot This Ordered PairPlot This Ordered Pair

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-3, -3)(-3, -3)

y

x

Plot This Ordered PairPlot This Ordered Pair

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-1, 2)(-1, 2)

y

x

Plot This Ordered PairPlot This Ordered Pair

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(1, -1)(1, -1)

y

x

Plot This Ordered PairPlot This Ordered Pair

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(2, -2)(2, -2)

y

x

Plot This Ordered PairPlot This Ordered Pair

-2

0-1

12

-3

3

-2 -1 0 1 2-3 3

(-3, -2)(-3, -2)

y

x

Now try it yourself.Now try it yourself.

• Can you do 1 quadrant or all 4 quadrants?

• Can you make a puzzle for someone else to do?

• Can you find the message?