# What Is a Radial Coordinate?

## What Is a Radial Coordinate?

The radial coordinate is the first number in the pair of numbers used to describe polar coordinates.

For example, in the polar coordinates **(5, 45°)**, the radial coordinate is **5** (the number on the left):

The radial coordinate is sometimes called the radius.

## What Does the Radial Coordinate Mean?

The radial coordinate tells you how far a point is from the pole.

If a point has polar coordinates **(5, 45°)**, the point would be **5** from the pole. The image below shows what we mean by a point being 5 units from the pole:

## Using a Polar Grid to Find the Radial Coordinate

A polar grid can be used to find the radial coordinate.

A polar grid is shown below:

A circle is shown in red. If we read along the horizontal axis (called the polar axis), we see that this circle is labelled **5**. This circle has a radius of 5. All points on it have a radial coordinate of **5**.

## The Radial Coordinate Can Only Be Positive

The radial coordinate can only be a positive numbers (0, 1, 2, 3...).

It does not matter which direction a point is from a point, the distance is positive.