In circle geometry, the radius and diameter are really important.

• Radius: This is the distance from the center of the circle to any point on its edge.

• Diameter: This is the distance across the circle, going right through the center.

And here's a key point: the diameter is twice as long as the radius.

You can write this in a simple math way like this:

$\text{Diameter} = 2 \times \text{Radius}$

Let’s look at an example.

If the radius is 5 cm, then the diameter would be 10 cm.