Surface area of sphere radius 6

Step by step

The question

Question: find the surface area of a sphere (a ball) with radius 6.

1 Use the rule

Cut the ball in half.

The flat circle inside has area π × r².

The skin of the ball covers exactly 4 of these circles.

Like the peel of an orange.

π is a special number for circles.

It is about 3.14.

So the surface area is S = 4 × π × r².

Now put the numbers in: r = 6.

6² means 6 times 6.

That is 36.

So S = 4 × π × 36.

4 times 36 is 144.

So S = 144π.

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.

144 times 3.14 is 452.16.

So the surface area is about 452.16 square units.

Let's look back.

First: use the rule.

Last: about how much.