Area of circle radius 3

Step by step

The question

Question: find the area of a circle with radius 3.

1 Use the rule

π is a special number for circles.

It is about 3.14.

The area of a circle is π times the radius squared: A = π × r².

So we write A = π × r².

Now put the numbers in: r = 3.

3² means 3 times 3.

That is 9.

So A = π × 9.

We write it as 9π.

We keep π in the answer.

That is the exact answer.

2 About how much

To see about how much, put 3.14 for π.

9 times 3.14 is 28.26.

So the area is about 28.26 square units.

Let's look back.

First: use the rule.

Last: about how much.