Circumfrence of a circle

The circumfrence of a circle is the length all arund the edge of the circle. Let's start with this question:

Find the circumfrence of this circle.

Ok, so the first thing we need to know is this formula:

Cirumfrence = 2πr

The symbol π is called "pi" and it is a constant - about 3.142.

The letter r stands for radius, which is the distance from the edge of the circle to the centre. We can see here that it is 3cm.

So, multiplying all of these, we get:

2 x (π x 3) = 6π

6 x 3.142 = 18.852

So, the circumfrence is 18.852cm. Here is a quick quiz to test yourself on this: