How To Calculate Circumference

The circumference is defined as pi multiplied by d, which is the diameter of the circle. This is equal to 2 multiplied by r multiplied by pi. Because the radius is 2.

2 times the radius equals the diameter.

So we can use either this or this to work out the circumference. let's look at an example. Let's say we have a circle with a radius of 5 centimeters.

We can use this and this to say the circumference is equal to 2 multiplied by pi multiplied by 5. This, we can simplify down to 10 pi, because we have 2 multiplied by 5 multiplied by pi. Now pi is an irrational number.

We can leave it in this form and this is correct. However, if you would like a shortened decimal answer, this is approximately 10 multiplied by 3.14.

This gives us the answer 31.4 centimeters. Always remember your units.

should have units here as well because this is a distance around the edge of the circle.

Let's try one more example. Let's say we have a diameter of 20. So diameter is 20 centimeteres.

Now we can use this to work out the circumference. It's very simple.we substitute the 20 in for the d here and we get 20 pi centimeters. If we want to simplify this once again, use 3.

14 for pi and we get 20 multiplied by 3.14 which gives us 2 times 31.1, which gives us 60 plus 2.

8.62.8 centimeters. And that is how to work out the circumference of a circle.