Pi time!

This one!

Pi, good old pi, or 3.142 as we often use.

In circle work particularly, we use **π **to help with our calculations.

You might use the **π **symbol on your calculator, or use 3.142 instead.

Here, we are going to look at leaving answers in terms of **π **

**Find the circumference of a circle with a diameter of 6 cm. **

Leave your answer in terms of **π **

The** formula** for finding the **circumference** of a circle is** π x diameter**

This is where the joy comes in - no working out to do. We know the diameter is 6 so we just write: **circumference = 6π**

**Find the area of a circle with a radius of 3 cm.**

The **formula **for the** area **of a circle is **π x radius x radius **or** πr²**

Here, all you have to do is find **radius x radius **and put **π **after it.

3 x 3 = 9 so the answer is **9π**

You might be asked to calculate something a bit different and leave your answer in terms of **π **

For example, what is the length of the curve of this quarter circle?

You will have worked it all out and let's say you have an answer of 9.424777961

To convert this into terms of **π **just divide your answer by** ****π **

It is best to use the **π **button on your calculator, as it will sometimes round it up for you.

Answers are usually shown to the nearest whole number.

So our answer here is 3**π **

Any calculation you have to show in terms of **π **just divide by **π **

Did you know that 3.142% of sailors are pi rates!!