How_To_Be_Good_At_Math

248 GEOMETRY •^ COORDINATES

Coordinates

Coordinates help us to describe or find the position of a point

or place on a map or grid. Coordinates come in pairs, to tell

us how far along and up or down the point is.

Origin

Point

The x axis is

horizontal

The y axis is

vertical

1

2

3

4

5

6

0

1

2

3

4

5

6

1

2

3

4

5

6

x

y

1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6

Coordinate grids

Finding the coordinates of a point

The position of any point on a grid can be described by its coordinates.

We write the point's coordinates

as (2, 3), which means two

squares along and three up.

We put coordinates in brackets.

To find the coordinates of A,

first we count how many

squares it is along the x axis. It is

two squares along from the origin,

so the x coordinate is 2.

Now we read up the y axis to

count how many squares up it

is to the point. It is three squares up

from the origin, so we say that the

y coordinate is 3.

A A (2, 3)

This grid is called a coordinate

grid. It's made up of horizontal

and vertical lines that cross, or

intersect, to make squares.

The two most important lines

on the grid are the x axis and

the y axis. We use them to help

us describe the coordinates of

points on the grid.

The x axis is always

horizontal, and the

y axis is vertical.

The point on the

grid where the

x and y axes intersect

is called the origin.

Coordinates are

always in brackets

The x coordinate of A is 2,

which is two squares along

The y coordinate of A is 3,

which is three squares up

0 x 0

y

x

y

x

y

In a pair of coordinates,

the x coordinate always

comes before the y

coordinate.

248_249_Coordinates_plotting.indd 248 29/02/2016 18:05