# Geometry » Coordinates

## 2D coordinates

To the right you can see a coordinate system with a number of points. You always first read off the horizontal coordinate. In this case on the `x`-axis. Then you read off the vertical coordinate. In this case the `y`-axis. These two coordinates are always separate by a comma. So (`x`, `y`). If the point has a name (a capital letter) you write it immediately in front of the first bracket. Use no marks/signs between the capital letter and the first bracket.

The first five points in this coordinate system have the following coordinates:

A(2, 0) | B(2, 4) | C(5, 2) | D(7, 0) | E(0, 7) |

### Broken numbers:

If you have a point that is not on a grid point and the `x`-coordinate is therefore for example 1.5 make sure you make a legible difference between your decimal dot(s) and the comma.

You can also choose to write fractions instead of decimal numbers.

In countries where a decimal comma is used, the semicolon ( ; ) is used instead of the comma to separate the two coordinates.

Countries using a decimal dot: F(6.5, 5) or F(612, 5)G(4.5, 6.5) or G(412, 612) |
Countries using a decimal comma:F(6,5; 5) or F(612, 5)G(4,5; 6,5) of G(412, 612)Note: The semicolon can always be used. Even if there are no decimal numbers. |

## 3D coordinates

On the right you see a drawing of a solid. A cube, to be precise.

Just like you can use coordinates to indicate locations in a 2D coordinate system, you can also indicate points in space with a 3D coordinate system.

The only thing we need is another axis. This axis is called the `z`-axis. With this extra axis you have a `xyz`-system. See the drawing.

Indicating a point on the cube is done in almost the same way as in a 2D coordinate system. The coordinates are between brackets and separated by a comma ( , , ) or a semicolon ( ; ; ).

The coordinates are written in this order: (`x` , `y` , `z`).

*Example*

`E`(4, 0, 4)

You first go 4 steps towards the front, always starting in the origin. That is the `x`-coordinate. You are in point `A` then. Next you are going 0 steps towards the right, that is the `y`-axis. So you stay in point `A`. Finally you go 4 steps upwards, that is the `z`-axis. You arrived in point `E`.